I have not had a chance to check all of these out, but they sound interesting:

Footnote - Has deal with National Archives where you can view almost anything in the archives

Hard to Find 800 Numbers - Just what it says

Wink - People search engine that references popular social networking sites. Sounds a lot like SPOCK

Lumosity - Play games that have been lab tested to improve memory, attention, processing speed and cognitive control

Top Secret Recipes - Recipe clones from various famous chains and products

The World's Healthiest Foods - Information on how foods affect your health

I Can Has Cheezburger - Cat pictures

BullPoo - Online community for investors

Indeed - Job website

Trulia - Real estate website

The Bargainist - Scours web for best bargains, coupons and free offers

Do My Stuff - Contract out small jobs and chores

Roadside America - Quirky touristy activities in various areas

Wikitravel - Travel research site

Yapta - Track ticket prices for airlines so that you can attempt to get a refund if you purchased high

DZone - Developer website

ProgrammableWeb - Keeps tabs on mashups and open APIs across the Web

Website Grader - Sumbit a url to be graded and obtain suggestions on improvement

Everything USB - Gadget blog for USB tools

AppScout - Place to find software, tips and tricks

MakeUseOf - Quick summaries of available web applications and how you might be able to use them

Nolo - Get legal documents, advice and information

Gawker - Track celebrity news