First, I don't call that "ugly" but "retro." That said, it is a standard size, so check out Home Depot or Lowes to see what other shades come in that size.

Personally, I don't think I would bother. I'd use lamps instead and put on the overhead lighting only when needed, like on cleaning day or searching for a small dropped item. The reason isn't the lights, but the ceiling. Those tiles are really unfortunate in a residential setting. I've seen them look a little better painted, but often landlords don't allow that. If I were living with that ceiling, I'd ignore it as much as possible and not draw attention through ceiling lighting.

I ended up replacing the entire lighting fixture for my ugly rental overheads. I bought inexpensive ones from IKEA (about $7 each). It took less than 10 minutes to swap it out (lots of YouTube videos on how) and that gave me some additional flexibility in getting something I liked.

Heathah has the right idea. By the time you buy new glass domes, you can replace the entire fixture. Sure, it's money lost, but what price beauty? Your landlord may even split the cost with you. Check the big hardware stores for replacement domes that might fit if you'd rather not replace the entire fixture.

Somewhere on this site I saw an idea of pinning a scarf to the ceiling over the light fixture. Been meaning to try it myself.

Seriously? Every hardware and home improvement store on the planet has tons or replacement shades on their shelves. Not a very thought provoking question AT.

It's an ugly ceiling and probably it's better not to draw attention to it with some kind of fancy light fixture. Better to stick with the unobtrusive one and just accept it for what it is. I like what angelinethebaker says - concentrate on finding nice lamps that you can take with you and use them for most of your lighting.

Sorry if this sounds unsympathetic. I know quite well how I can get focussed on one thing I hate (ask me about the tile in my main bathroom sometime) and just be unable to get over it. But, in my experience it's almost often better to distract the eye from the things you don't like, than to try too change them.

Where are you renting that has acoustic ceiling tiles? Those are so much worse than the light fixtures.

I was thinking the same thing TEXASOTA: At first, I thought this was a school. I agree that it's the ceiling that's unattractive so don't bring attention to it.
Bring your beauty down to your furnishings and accessories and hopefully, no one will notice the light fixture but I can't say they won't notice the ceiling. :o(
So if you decide to cover the ceiling instead, try covering it in a beautiful textile. Something you can easily remove if you ever terminate your lease. I think the light won't look so bad then. Best of Luck.

When we rented I put paper lanterns (that were made to go over lighting fixtures). I recently saw a cool fix for ugly ceiling fan light fixtures, capiz shells that hang from the ceiling. You could just put little hooks up in the ceiling and affix the capiz shell shade to that. There are also DIY's on making wax paper capiz shell ceiling light fixtures you could look at online. And, there are also places online that sell shades and chandeliers to go over a simple lightbulb. Lighting is very important, I would put something over it, make sure it's safe and it will be easy since it's such a small light fixture. Be sure to put other lamps and lighting all around your home too. They will distract the eye.

btdt. http://www.apartmenttherapy.com/how-to-improve-139579

Like others, I think that the ceiling is 100x worse than the light fixture. (And, to be honest, I actually like the light fixture!)

That being said, I saw various sizes and styles of replacement shades in Home Depot yesterday. Perhaps take the one that's on there now to the store with you to be sure you get the right size, if in fact you want to go the replacement route.

I agree that the ceiling is far worse than the fixture. buy some lamps and not ones that point up.

I had a light in my apartment with no cover so I jury rigged a lobbo shade onto it and it looks very cool.

Overhead lights for seeing where you are going, not really to light up a room for use. They give a very bland look to the room. Small rooms look smaller, larger rooms look utilitarian and flat.
Lamps around the room (a mixture of floor and table) will open up the space, creating pools of light that invite the eyes in. Don't get anything that directs a lot of light up, like torchiere lights as they direct all the light up on the industrial ceiling.

Love an pretty oriental umbrella hung upside down, Open one up and secure the shade open and then cut the stem [works well on bamboo]. Before hand, take off the glass shade and decide how to hang in advance. Some fishing line thru screw holes for the sahde of existing fixture might work and need a hole thru or small eye bolt into the end of the bamboo rod of paper umbrella. Gives a nice light!

If you go for a new fixture, make sure the existing is connected to a junciotn box secured above the tiles with metal hanger rod or conduit tube before you hang anything else except such things a larger paper shade fixtures and such.

This is a great site for lamp and light parts.

http://www.grandbrass.com/glass.cfm

For the people wondering about the acoustic ceiling tiles- I have lived in several places with these types of ceilings. It is usually apartment complexes. One such complex was an office building in a previous life. You will also find them in attic/basement apartments, as it is a flexible solution for homeowners to access to electrical/plumbing, while still being able to have rental income.

You could do this scarf cover over just the fixture, or a series of scarves or fabric pieces over the whole ceiling. (Originally from an AT! post)

http://www.apartmenttherapy.com/three-cheap-easy-fixes-for-renters-with-ugly-light-fixtures-171954

When I saw the headline, I thought that this post was going in a different direction: towards items that would not clutter up a small space. (I understand the Japanese are experts at giving gifts that will not become clutter, such as expensive Scotch.)
You know, ideas like drink, comestibles (great chutney, great cheese, great shortbread, fresh pecans), movie tickets, iTunes gift cards, gas cards, and, yes, museum memberships. Theater tickets, concert tickets. Plane tickets!!

The comments about the ceiling are right on target. Although even in a rental i would completely replace the fixture (and save the old one to swap back before i leave) I agree the ceiling is your biggest issue.

That said there are several ways to deal with this type of ceiling depending on how much work/ money you want to invest.

I would start thinking about inexpensive materials that you could cover them with, if you can't find a fabric cheap enough, try using aluminum foil...I've done this in an office before, and its all about how well you apply it, if you can take the entire tile out, lay it down flat and cover it with foil making sure its flat and clean looking. ( I had the dull side visible, but if you want it more glam, the shiny side could work too.)

if you are more of a handy person and either have a saw or can sweet talk the big box store helper into cutting for you, you could get some Luann plywood (1/8 in ply that's also referred to as "door skin") cut to size, stained and just dropped in place of the tiles could look stunning.

and then perhaps the very easiest is to remove all the tiles, paint THE BACK SIDE and put them back upside down, when it comes time to move, flip them back over and the Landlord will be none the wiser.

Are these in a kitchen? There is a relatively inexpensive faux tin panel you can buy and tack up over the acoustical. They are light-weight and look pretty good. You would still need to find another light cover though.

As a fun comment, I googled " temporary cover for acoustical tiles" and the first several hits were all from AT. Evidently, its a fairly common problem. You might find some more solutions in 'back issues'.