I went looking for a font for a project I wanted to do and was happy to find myfonts.com, a great online font store. They have a big collection of fonts from good foundries and an easy-to-use interface for browsing and buying.
The central problem in font selection is "I need a font that looks like this". myfonts.com tries to help with that - fonts grouped by category, a "fonts like this" button, and even the ability to browse other user's albums of selected fonts. Alas none of it quite works. But if you stumble around you can often find what you need anyway.