O'Reilly maker. No descriptions, just look at the images I created and you get the idea.

Some other ones:
Women's Psychology
Facebook

Thx to Simon, I now find a new hobby--work out problems in Project Euler. Project Euler pose a lot questions, currently, 163 of them. by complete a question, a person can gain some genius level and access to the forum topic for that question, which features a huge amount of resource of how to do the question efficiently.

Many fields of mathematics can be learned from Project Euler, and after correctly answer all 163 questions, a amazing bragging right is up for grab. I struggled for an hour and solved 12 problems, a link to my current genius level. Wish I can get my name on money like Leonhard Euler.

Tsung recently creates a new service, SiteTag. The service require a bit of Javascript embedded in the website, It finds out the most popular keyword for your site from referrals, and calls them tags. My profile page shows 2 days of data collected. It doesn't look really impressive, since the common English prepositions are counted as tags...

Because this is a new service made in a hurry, I can see the future improvements, small bugs will be fixed really soon. My talk with Tsung clearly states that any suggestion will be taken seriously. Wish the future of SiteTag be bright.

SmartPageRank. Love it!! I Love it's Backlink analyzer!!
All the pages link to your site will be displayed with their pagerank, you can use this to find friend sites with high PR.

According to the image, Performancing should be the major contributor to my pagerank. I own my life to them.

FilesTube, a new search engine for files hosted in various file hosting sites like Rapidshare.

I don't find it useful, yet.