Tomboy

A sleek look, a wiki-like behaviour with CamelCasingHyperLinks, an efficient searching system ... Tomboy is a valuable tool to keep tracks of your thoughts through your computer, prepare documents, structure your work, etc. If anything, it may be a bit weak on import/export functions (blogs, wikis, Latex, etc.), but this isn't much surprising for a recently launched application. It makes me wish I was fluent enough in C# to hack new features around...