I wanted a simple web interface to act as a nice overview/front page for my XBMC HTPC. I couldn't find anything that suited my requirements so I created something myself.
You can find more information and setup instructions on the project homepage.
There's also a thread on the XBMC forums.
Customisable applications module providing quick access to your web interfaces (e.g. SABnzb+, SickBeard, or whatever else you want to link to)
Recently added episodes module - click an episode to play it in XBMC
Media library browser - browse your movies and TV shows, and click to play in XBMC
SABnzbd+ module which appears when something is downloading and hides again when finished - shows you what is currently downloading, speed, time/MB remaining, and a progress bar
Currently playing bar with play/pause/stop controls
trakt.tv module which shows you what people are saying about the episode or movie that you're watching (requires a free trakt.tv account)
Sickbeard module which allows you to browse upcoming episodes (coming soon: the ability to manage Sickbeard from Maraschino)
Disk space module showing you used/remaining space on your various drives
Full-screen background image changes to the fanart of what you're currently watching (optional, can be turned off)
Customisable from within the application itself - no need to mess around with settings files
Uses Flask and some other awesome technologies (SQL-Alchemy, LESS CSS). Just set up Maraschino.py to be served using Apache and mod_wsgi or however your prefer to do it.
This is an early-stage work-in-progress - if you run into any problems then let me know, perhaps I or somebody else can help (at the very least, bug reports are always welcome!)
If your HTPC is an ice cream sundae then Maraschino is the cherry on top.