These sites were mentioned on LM-Net today, and I hadn't heard of them. They're both searchable web directories of Web 2.0 apps (who can keep track of all of them?!)
Go2Web20 According to their "About" page, the site archives over 2,500 web 2.0 apps. You can search by the type of app you want (e.g. timelines) or use the tag cloud. I found typing in the search tool somewhat slow and clunky (though I enjoyed the sound effects), and it seems overly precise.
For example, typing in "time" brought up 13 time-related apps. However, "timeline" only brought up XTimeline, even though there was another timeline application (TimeToast) in the earlier set of apps. I assume that's because it used "timelines" as part of its description, rather than the singular form of the word.
Simple Spark is an interesting addition to the growing set of social networking sites. I never would have thought of social app-ing, but what a no-brainer for anyone involved in staff development!
You can search the database of applications by keyword, category, or sub-category. You can also add in your own applications, if you've create any. The free registration creates an account where you can save the apps that interest you, write reviews and share the list with friends.
It might be somewhat hit or miss with the contents. I searched some obvious tools, finding Flickr listed on both sites, although neither had Jing. Simple Spark had VoiceThread; Go2 didn't.
I plan to do weekly, short tech-tutorials next year; Simple Spark may be a good tool for sharing with the other teachers. I'll keep you posted on that!