Home Depot sells a radiant floor heating pad of sorts.
You just unfold it and put flooring over it. I haven't tried it but it looks easy.

slippers?

I would also consider putting foam underlayment down under the rugs- it's what they sell to prep for floating floors.
We have a frigid dressing room and I had an extra bamboo rug that I put down- you'd think it be really cold, but the bamboo doesn't really hold cold- or the heat.

An oil-filled electric radiator. I have a small delonghi unit in my bathroom (that is otherwise so deathly cold in the winter). I keep it on low and it seems to take the edge off the chill at relatively little expense. Depending on how large your apt is, a larger oil filled electric radiator could make a big difference.

I also run a small fan to circulate the warm air coming out of my regular wall-radiator, too. Otherwise it just warms the floors around the radiator...

I had tiles in two of my three undergraduate dorms in New York and even if the apartment was warm the floors were cold. This could be because one of those two buildings was orginially a prison, but I doubt anyone designs intentionally cold floors.

I second the slippers and socks solution in the short run. In the long run, I suggest a trip to your nearest Ollie's, I picked up a 25 ft by 18 ft black carpet for $85 and enough foam padding to go under it for $30. Buy something neutral, cover the tile, lay the rugs you have over it and keep bundled!

Add another name to the slipper side. I'm trying to do the same thing in my current apartment - but its just not working. Rugs help a whole lot, but they can't cover everything.

Slippers (and an at-home-hat) make HUGE differences in the winter time. Just think of the slippers as a rug you take with you :)

i vote for slippers and heaters with fans too! because in the summer when it's hot, you're going to be annoyed you spent so much money for extra rugs and pads and you'll appreciate the cold tile floors then.

From someone living in a first floor Boston apartment (read: over cold basement on wood floors that have no insulation under them), indulge in some nice slippers. It will solve your entire problem. Keep rugs where you will sit on the floor (livingroom) or come into contact with the floor (bathroom), but otherwise, there is no need to cover every inch of your floors for the occasion that you might walk on that particular inch of space. Just cover your feet. Keep a couple different sizes of washable slippers on hand for guests as well (ikea used to have cheap ones, yes, ikea... but you can find cheap slipper socks anywhere). Enjoy!

I'd check for drafts in the doors too. I had a draft coming from the exterior door in my kitchen and once I plugged that up, the air and floor temperature in there both went up significantly. The floor is still colder than the rest of the apartment (partly coz it's linoleum instead of wood) but it's helped a lot.

Not sure this is a great product, but they claim to warm your floors.

http://cozywinters.com/shop/rug-heat.html?source=base

The small one only puts out 65 watts, which isn't much heat, but maybe someone on here has a better review of this.

I also agree with checking for drafts.

-slippers and warm woolen socks
-small carpets in the bath or next to the bed where you step on with naked feet
-check drafts at doors, windows. Curtains help to keep the warmth in but keep them open in the day if the sun shines.

If it really works, that rug heater is tres cool.

Relocate to Boca til Spring.