tomboy-ng is a note taking app that works and syncronises between Linux, Windows and MacOS. It will also Sync to Tomdroid on Android. It features a rich text markup, printing, spell check, backup and snapshot capability. Import and export (plain text, RFT, MarkDown). It has Tomboy's automatic linking between notes, searching abilities, NoteBooks and a similar interface.
Importantly, tomboy-ng has little or in most cases no dependancies and so is an easy and lightweight install. Most people use the binary install kits but you are welcome to build from source.
Please see the Wiki for further information.
We use GitHub to store sources and track bugs, see Tomboy.
The tomboy-ng homepage also is part of the Tomboy homepage here.