CalDavZAP is a CalDAV Web client with a powerful event/todo editor. It is compatible with Safari, Webkit, Firefox, Opera (15+), iCab, and Chrome, and supports all major CalDAV servers.
Lightning is a calendar application which works with the popular Mozilla Thunderbird and SeaMonkey mail clients. It lets you manage multiple calendars, create your daily todo list, invite friends to events, and subscribe to public calendars.
A GUI client for Git, Mercurial, and SVN.
A graph visualizing tool.