MochaRep
MochaRep is a simple reputation system designed for my private server. Seeing as any other plugin that served this purpose was either too advanced or out of date, I decided to create my own. When I say simple, I mean that it is really just a few lines of code. I'm still working on it - namely the ability to assign different permission groups to different levels of reputation and the ability for the community to determine the reputation of other users through some kind of voting system. Right now, it is possible to get and set the reputation for players... and it is possible for other plugins to get the reputation of any user.
Claiming
With the latest version, it is now possible for users to claim chunks with the /claim command. When a chunk is claimed, other players cannot place, break, or otherwise modify the landscape within the chunk and mobs cannot spawn. In the future, it will be possible to configure exactly what and how things can happen within your chunk (e.g. a chunk that allows spawning of skeletons from spawners for creating of mob farms), it will be possible to a split a chunk between different people and control permissions for different people, and it will require reputation every time you claim a chunk. Further down the road, there will be ways to get and lose reputation.
Commands
/rep [user] - Lists the reputation of the given user
Permission: mocharep.rep
/rep [user] [set|plus|minus] [value] - Sets, adds to, or detracts from the given user's reputation
Permission: mocharep.rep.modify
/repreload - Reloads the MochaRep reputation file, updating each players' reputation if necessary
Permission: mocharep.reload
/represet - Resets the reputation for every player to the default, zero
Permission: mocharep.reset
/claim - Claims the chunk that you're standing in
Permission: mocharep.claim
/unclaim - Unclaims the chunk that you're standing in
Permission: mocharep.claim
/who - Tells you the owner of the chunk that you're standing in
Permission: mocharep.who
Repository
The code for MochaRep is stored on GitHub. Note: It is currently not up-to-date with the latest version of the project because, quite frankly, I am very bad at using version control software.

