They are called the 'monster fluffy' towels from a place called Detailers Paradise and I was very impressed with them. They really excel in any number of detailing tasks both interior and exterior.

http://stores.detailersparadise.com/catalog/Prima%20Monster%20Fluffy_1.jpg

I just buy the pack of 8, 14x14 microfiber cloths from Wal-Mart for 5 bucks...they are great

I've seen the ones from Walmart and they're fine for doing windows or your interior (except clear plastics), but I would never use those on paint. There are many, many different qualities of microfiber as far as the different percentage of the raw materials, the weight, the weave, the fibers per square inch, etc. and the cheapo ones are usually not the best choice for your paint or other delicate surfaces.

There are many selling high end extra thick microfiber towels, stay away from the cheap towels until as said you use them for glass, because they will scratch your paint over time. :)

I buy a huge pack of micro-fibers at Costco. They are great on anything...haven't had a scratch yet.