IIRF - an ISAPI Filter that does rewriting and proxying, like mod_rewrite and mod_proxy for Apache. C/C++.
CleanModQueue - a tool to automatically clean your reddit moderator queue. .NET, C#, WinForms, REST, JSON, System.Net.Http.
gplus - a wordpress plugin that displays your most recent Google+ activity. PHP, REST, JSON. You can see this running in the sidebar on this page, above.
flickr_eyecandy - a wordpress plugin that displays a random flickr "Eye Candy" image, selecting one photo from Flickr with the tag or tags you provide. PHP, REST, XML. You can see this running just above, on this page.
XPath Visualizer - a Windows tool that helps you visualize XPath query results. .NET, C#, WinForms, XML
ReloadIt - a Windows tool that reloads an IE tab, based on a change in a filesystem file. Works like Mac's Live Reload, but for IE. .NET, C#, WPF.