BOOB tops are great.
http://www.milkface.com/

I liked Bravado bras...not entirely stylish but very very comfortable. Good luck to you!

You can find some cute things at motherwear.com that aren't expensive, and babystyle.com has some nice items in their transitional wear. I got a Le Mystere nursing bra there which I really loved. Another thing you can do is to layer a camisole with a built-in shelf bra under regular tops, and then you can pull the shirt up and the camisole down at the top, and it acts like a nursing top, keeping you covered but allowing your baby to nurse unobstructed.

This isn't a clothing comment... but certainly related. To avoid giant nursing pad circles, or boob diapers, I wore lilypadz. They were AMAZING! I could wear my prepregnancy tops and feel like myself again. They were a miracle for me.
http://www.lilypadz.com

Then, as far as clothing goes.... I just wore regular shirts and lifted up one side discretely.

I lived in Boob shirt for the first 6 months of nursing. They're not cheap, but they made public nursing much easier. I purchased mine at http://www.milkface.com.

for serviceable, casual tops check out http://www.Expressiva.com. i like their stuff for hanging around the hood on the weekend.

Hugeamondo nursing clothing resource here: http://www.kjsl.com/~beanmom/nursing.html

I went nuts on nursing clothes with the first baby. But with the second and third, I just made sure I didn't wear anything that couldn't be yanked up or pulled down.

I wore nursing tank-tops from Target and layered them with dresses and tops that have that wrap-style, or just t-shirts. With the wrap tops I just pull one side over and unclip the tank top and held a burp cloth or just my hand over the part of my breast that was visible, because I don't believe babies should be covered with blankets while they're eating (and my baby wouldn't hear of such a thing either, because i tried once). If I wore a t-shirt and pulled it up from the bottom, the tank-top covers my belly. I think they were around 14.99 each, and I got 2 black ones, a white one, and a grey one. I got them a year ago and even after wearing them almost every day they are in excellent shape.

i lived in about six tank tops from glamourmom.com. i basically just bought every color that appealed and wore them without a bra every single day for a year (i know, i know, believe me i've since destroyed them). but they were super-comfy, good for layering under sweaters or just wearing as a top, and the boob-exposure mechanism was by far my favorite from any other tops i saw.

My Glamourmom tops were also my staple. They are a little pricey, but totally worth it.

I'm jealous of anyone who can wear a shelf bra!
If you need a little more support and want a tank, Bravado makes tanks too--much more supportive than most others, and quite comfy. But be forewarned that the construction is such that your entire boob is let loose on the side you are nursing on. So I love them as a layering piece or for around home, but not on their own while we are out and about.

I actually spent a bit of $ buying Boob and other nursing tops when in the end I found that the best thing was just regular shirts that lifted up but weren't too loose. After a while as my son got more stimulated by his surroundings, he would just pop off while eating and if I was wearing a nursing top I would be completely exposed with my nipple hanging out. At least with a regular shirt I could quickly pull it down and be more discreet.

I like these from ILM, especially that they're designed by an NYC mom. http://www.ilmfashions.com/

Ditto on the Glamourmom tops!