The following MoinMoin extensions were created by SeaPig members.
BlogEditCode -- a simple action which makes editing pages a bit more Blog like (BrianDorsey, SteveHowell)
LocalSiteMapCode - shows tree-like listing of nearby pages (SteveHowell)
OutsideLinksCode - lists all of the links on a wiki which lead outside the wiki. (SteveHowell)
PageSignatureCode -- a little macro which shows a list of all MoinMoin wikipages and their visual signature (AsimJalis, BrianDorsey)
RecentBlogsCode -- a simple macro that shows recent blog entries anywhere in the wiki (AdamFeuer, SteveHowell)
See MoinMoinPatches for other places hosting MoinMoin extensions.
MoinMoin is quite easy to extend. There are two major types of extensions:
actions -- actions do something outside of page rendering, and they're available on every page
- macros -- macros generate special page output (normally without side effects), and have to be placed manually on a page to be available
To create MoinMoin extensions, you don't have to muck with MoinMoin's internals; instead, you just create the Python modules and drop them in appropriate folders. The best way to get started is to read the other extensions that come with the MoinMoin distro, and then hack them up to your taste.
MoinMoin is fun to do pair programming on. Many of the Seattle extensions were created used pair programming. We're keeping a list of ideas and people interested in pairing on them here: MoinMoinIdeas For guidelines and help on coding for MoinMoin, see MoinDev.