I love taking a look at fresh web 2.0 sites and then tracking their development, perhaps even taking part in them in the form of comments, feedback and email exchanges. I have a few favorite sites I get the low-down from about these new sites, and since I know most of you also love these apps, I thought I'd share them with you.
My two favorites are Go2Web2.0 and Listio. Bot sites are great for finding new companies, but I recommend subscribing to their feeds to get the latest news. Actually Go2Web2.0 is a very poorly designed site, and navigating is quite hard, RSS is way easier. It's pretty, but it's really slow and full of weird bugs. Listio is better designed, it is a good place to just browse around.
Another site I have used in the past is eConsultant's page on web 2.0 sites. It has over 1.200 sites, but is not really updated, at least of what I've seen. It is a huge directory, so you can browse through it and try any service whose name catches your fancy. I think this was the first directory I ever visited and I can thank it for my obsession.
Listable is a good resource as well, but it's very hard to find what you're looking for. It is a bit riddled with spam, but if you can get to a good entry here and there. I recommend searching for specific web 2.0 apps, but even then it's hard to find relevant lists. I assure you that when you do though, you will have a good time.
Update: Go 2 Web 2.0 is no longer available, the website returns a not found error when you try to load it in your browser. We have removed it from the list as a consequence.