Suggesting an addition http://viewdns.info/ - A collection of free DNS tools.

I find it kind of funny that all of the tools live online... Not in a bad way, just a kind of "at the end of the day, this thing I'm building has to serve real people over this thing we call the internet" as opposed to doing everything with offline tools.

Puts everything into perspective I suppose :)

Cool, this list showed me APIfy, which has an intriguing service I'll probably make use of. APIs out HTML sounds great.

Great list.

Slight misspell of pingdom.

Web Engineer?

This is a really great list!