Notes
Notes is, well, just note-taking. It's use should be fairly obvious: navigation is on the left, entries are added from the bar at the top.
Entries can be named and tagged, and entries can be browsed chronologically, alphabetically, or by their tags. There are convenience buttons at the top to go back or forward by a month or a year in the chronological view.
Named entries can be subdivided in the navigation by using colons in the name. For example "Notes: Physics" and "Notes: Chemistry" will result in a "Notes" list in the alphabetical navigation-list, of which Physics and Chemistry will be links leading to the relevant entries.