Well, here are the websites i have on my Kindle for bookmarks.
Gmail (m.gmail.com) - good email client.
Facebook Mobile (m.facebook.com)
xkcd (m.xkcd.com) - webcomic, that has referenced the Kindle before, mostly it's Hitchhiker's Guide-like qualities.
) - Works great, can even reply on the forums with it.
Ireaderreview (ireaderreview.com) A Kindle/ereader news and speculation blog.
MLIA (mylifeisaverage.com) - Doesn't format perfectly, but you can read the MLIAs, which should be all that matters with that site.
Cracked (m.cracked.com) Comedy site; I prefer the full version, but this works too.
Weather Channel - (what ever the default bookmark is)
Boing Boing (m.boingboing.net) Tech website
BBC (again, prebookmarked)
Slashdot (slashdot.org/palm) Another Tech Website
Skweezer (skweezer.com) A site that allows you to make not properly formatted sties format.