zoho mail Webmail provider that supports custom domains (see also: mail.live.com)
mx domain lookup Used it to debug issues when setting up custom email domains.
image proxy Caches and resizes images for websites
picozu web image editor I like this one because there is no sign-up and you can drag and drop onto it.
http://hpr.dogphilosophy.net/test/ HTML5 Audio support test