My principal source of recipes is Cooking Light magazine. (Not because I am particularly interested in diet food, and neither are they.) When I was a magazine account rep I had a lot of opportunity to read the whole category of food magazines over many years and Cooking Light is the best, followed closely by Fine Cooking. I don't like Bon Appetit, Cook's Illustrated or the other highfalutin' types because I'm looking for recipes for every day, not just special occasions.
Until now I have been tearing out the recipes I like, gluing them to pages and putting the whole shebang in a binder. It's a real time-sink though, and over the years it's gotten harder to find what we're looking for because we had no real categorization scheme. Plus stuff gets splashed up and dirty because we are still kitchen barbarians.
Today I took the binder and fed all the recipes from Cooking Light into Myrecipes.com, the parent site of Cooking Light's publisher, which includes recipes from many other food magazines. I now have all my recipes categorized and sorted, available on the kitchen computer whenever we need them. You can make changes, add notes, do whatever you like to the recipes. This is going to make menu planning way easier, now that we don't have to flip through the flipping binder all the time.
The other site I use is Allrecipes.com. Cooking Light doesn't have the baking coverage that this site has. It's been around practically since the Internet was born. I have a recipe box there too. Now if I could just manage to digitize my recipe books, that would free up some space in my tiny kitchen.