Update: Read an updated reference of 12 notes applications here.
Tomboy
Tomboy is a feature-rich notes application for GNOME with support for spell-checking, links, font style and size, bullet lists, global shortcuts, and plugins. Tomboy will also let you search notes and export them to HTML. The plugins (called add-ins in Tomboy) include exporting to HTML, backlinks to see what other notes link to the current note, Evolution Mail integration, printing support, local directory synchronization.
