I have a couple of plugins for ExpressionEngine to help make an awesome platform even more flexible.
ForEEcast pulls it's data from Weather.gov and provides a five day weather forecast for your ExpressionEngine web project based on a target zip code.
Check out more about it here.
BasEE64 is an ExpressionEngine plugin that encodes and decodes data via the php base64encode() and base64decode() function.
Marker is an EE 2.x plugin that converts between Markdown and HTML. Both directions are supported, Markdown -> HTML as well as HTML -> Markdown. Markdown is the creation of John Gruber.