This is the best taskbar drag reordering tool there is. Coming in around 200K in RAM, and with no UI ... it lets you drag and drop even with "grouping" enabled, and can even reorder the items inside a group. Very fast, very intuitive, nothing I don't need.
Although it's nice to save the window position and size automatically ... it's frankly not worth an external library. However, this is a good sample of how to do attached properties, and if you have a general utility library that you include in all your WPF apps, this would deffinitely be a useful addition to it.
RRDtool is the OpenSource industry standard, high performance data logging and graphing system for time series data ... has interfaces in all the usual open source scripting languages
Make free calls from this web page to anywhere in the USA ... while a computer analyzes your conveersation and pops up web pages, news, images (*ahem*: advertisements) on the web page which are "relevant to your conversation" ... Free, but with a price.
Connect to WebDAV, FTP, Amazon S3, FTPS, or SFTP servers through a virtual drive which is a full file-system drive which works in DOS, PowerShell, etc.