Bukkit

sounds great! but what is the tool i select the corners with?

Sorry to keep flooding the page, but I had simple idea that I'm not sure if you've put in:

• A configuration option so that you can control what worlds can be claimed in.

@Err0neous

I quite like the way you're designing the plugin. In honesty, the addon idea is perfect; most complex functions could be made as separate addon - hence why the API would be very useful. As soon as I get the chance, I'll look into the code there. Safari on an iOS device isn't that good for browsing GitHub.

@Err0neous

Allow me to see if I understand the way you're describing your idea.

• Plots are owned by the town.
• Town administrators (mayors, co-mayors, etc.) can modify any plot they wish.
• Plots may be given to a member of the town by an administrator.
• Ordinary members of the town may suggest plots to be claimed.
• If an administrator adds the suggested plot to the town, the player who suggested it is added as the owner of the plot.

If that's how it works (and it appears to be, from my reading your comment), then I think that would be a great way to manage plots.
I do have a couple suggestions, though they may not fit with your plans for the plugin or may be a bit too complicated for your aim of simplicity.

• If plots aren't grid/chunk based (and if they are, just ignore this), you could do so. Though the fact that you can specify EXACTLY where you want your town claims to be is good for being exact, some people just want to be able to blanket coat an area in claims. I think it might be a good idea to, when people make a claim, have the plugin auto-claim the chunks or grid-areas that the claim is already in. Though if you did this (as a server owner), I would think it would require a configuration option to choose whether or not it auto-claims.
  • TL;DR: Grid/chunk based protection and when an claim is made, the chunks it is on are auto-claimed.
• As far as war goes, it could be quite simple. Every town in the war has to agree to go to war. Once you go to war, you can grief enemy towns and claim their land (both configurable, of course). Towns can withdraw from the war at any time (or some variation thereof), but there is a penalty of some sort for withdrawing - loss of land, loss of money, loss of resources, etc.
  • TL;DR: Take Factions' approach but make it better
• The members of a town can get a new mayor if they don't like their current one through electing him out or some other kind of mechanic.
• Make town permissions modular. Allow town administrators to create their own ranking system within the town and give each rank different permissions. Let's say Town A has the following ranking ladder: Mayor, Council, Civil Servants, Builders, and Citizens. The Citizens can build and destroy in their own plots. Builders can build and destroy in any plot. Civil Servants cannot build and destroy in every plot, but they do have limited access to the town treasury or can expand the town's borders. Council members have the same powers as Civil Servants but with the additional power of being able to vote on issues (such as taxes, new mayors, etc.)
  • TL;DR: Allow for towns to make their own ranks, each with its own permissions within the town.
• Eventually, I would like to see nations of some sort become a part of the plugin. It could make the war idea more interesting as well. Nations would add protection in a war event (members of the same nation can't fight each other). Towns could leave nations at any time (again with some kind of penalty).
  • TL;DR: Nations would be cool.

Again, I understand that some of these suggestions wouldn't be feasible, they're just things (or versions of things) I want to see in a town plugin and haven't seen.