Some websites I have found interesting (in no particular order):
Why do we have an IMG element? — Very interesting look back at the early days of the internet. Makes it a lot easier to see how we got to HTML5. Man, that Mark Pilgrim has been on a roll lately!
Hurl — Website for testing HTTP requests. Great for debugging APIs or making sure your headers are being set correctly. Plus, the source is free for all to check out.
After the Deadline — Website for spell/grammar checking text. Has an API so you could potentially plug this into any project where that would be useful.
memcache-top — Holy cow! Look at the size of those memecached databases! 30GB! I never really knew how much of a machine memecache was!
The Open Graph API: What Does It Mean? — Facebook continues its quest to take over the internet. Let’s fight this.
I’m not dead! — Speaking of Facebook, they recently came out with what has to be the stupidest feature of all time: now users who have passed away are even harder to find. Yeah, that way you won’t be sad! Anyway, they implemented this feature but then this guy’s friends claimed he was dead. Pretty funny!
Protovis — What appears to be a pretty awesome graphing library. This is my favorite example (make sure you move the red box on the bottom graph). Comes in at a whopping 258kb though.
Converting to data URLs — A script to convert files to data URLs. Pretty handy!