Here are some ideas for a rainy day / boredom killing. There are OpenBSD specific ideas on the OpenBSD page too.
Make OpenBSD's cwm window manager portable.
This would involve wrapping in autogrunk and porting the OpenBSD linked list macros.
The sources can be found in the OpenBSD CVS in xenocara/app/cwm
You could add a credit system to MPD for fair used in a shared environment. This would mean you would also need to add multi-user authentication.
As it stands, NCMPC does not resize itself when the terminal is re-sized.
Tomboy is a good idea for an app, but it links gnome grunk and is written in C#.
Write a replacement in something else without all the gnome and XML rubbish.
After a long talk on silc about this, apparently it is possible with NetBSD's “puffs” or XFS.