Missed Connections - painfully adorable illustrations of actual personal ads. Funny, charming, heart-warming and heart-breaking all at once. The artist is Sophie Blackall - and she has an etsy site, too. Go buy her stuff.
Dinosaurs and Robots - They had me at dinosaurs. This one is about all kinds of cool stuff...as in actual stuff. Like Roald Dahl's writing hut or a vacation home made from shipping containers, Ipod amplifiers, vintage advertising or Guinness posters. It's always different, unexpected and cool. As far as I'm concerned, it's why the internet exists.
Sketch for the Day - Artist Ira Robbins gives the whole world little glimpses into his everyday life and they're awesome. I love his people on the subway, and there's a dude in a hat that reminds me simultaneously of Walter Mattheau and my bulldog.
Forgotten Bookmarks - A guy who works in a used bookstore finds photos, notes, cards, and all matter of flat stuff in the books - and very kindly shares it online. Sometimes it's multi-page letters, others just a photo, but it is always interesting and voyeuristic. And makes you go through your own bookshelves to make sure you haven't stashed anything wacky in there. Recently, there's been a bunch of contests, which aren't all that interesting, but it's worth checking a couple times of week anyway.