Here's some sites which i find to work well on my kin TwoM. Some i've already mentioned in the feature phones thread. If you don't want to type these in, just view this thread on your Kin and visit+bookmark them.
http://m.bing.com/
Bing worked better than google mobile on the Kin's browser. On a TwoM, if you're in landscape mode, close the kb and view it vertical. Reload if you have to, now it should display the full list/menu. If menu items are too small, quick double tap on the menu.
Neat thing: If you search local businesses, or looked up a movie -> movie theater, you can call them by tapping the phone icons. I wish this worked on all mobile sites. And if you click the car icons, you get directions. The directions is great, one gripe, no zoom in/out.
http://m.local.com/
If all you need is a quick address, this is a faster way to get it. But no single tap phone calling 
http://m.whitepages.com/
Good default size on the kin.
http://i.word.com/
The best looking functioning online dictionary for the Kins.
http://www.wapedia.mobi/en/
A better looking/faster loading page than wikipedia's own mobile page.
http://www.gasbuddytogo.com/
http://translate.google.com/m
Google's translation engine is very good. Lacked the speech capability of the full site. Not a big deal since the Kin's browser can't playback sounds.
http://www.dslreports.com/mspeed?jisok=1
Bandwidth test. In case you're curiously bored.
http://www.onetrip.org/quip/?pass&go
Daily quotes. Nice font size. Interaction works. You can tap the date to load a new quote.
http://mobile.flightstats.com/
Basic, but works. I've bookmarked the flights page to directly search for flights.
http://www.gamesforthebrain.com/
Brain games! A few doesn't work, but most of them work. More under 'word games'. I found 'The Google Adventure' to be entertaining.
http://www.websudoku.com/
There might be better sudoku games out there, but this one is simple and give hints.
http://m.icq.com/
I have not tried this one. But if you still use icq, please give it a try and let us know how it works on your Kin.
Cheers! 