I'm currently using "American Whey", bought at GNC... Not the cheapest or best quality Whey powder, but I needed it in a pinch.
I'm going to try 'All the Whey'. Have heard some great things about it. Vanilla flavored powder is good in a glass of lowfat / skim milk, and it's a bit cheaper than the stuff I have now.
www.allthewhey.com