So, to do this we'll need answers to a few questions:
1) Who's on the organizing committee with me?
2) What forum do we host this in?
3) What are the entry guidelines? How many levels in a build, or should it be multi-level? What, besides the particular homebrew material being op'ed, is allowed?
4) What are the judging criteria? How many judges, besides the author? (I don't think the organizing committee should necessarily automatically judge, since I know I'd love to enter a few.)
5) What's the policy for editing the material mid-contest? Basically, what happens if the contestants discover that a mechanic is broken while they're op-ing? Does the author get to edit, or do they have to wait until the contest is over?
6) What types of things are being optimized? Just classes, or feats, etc. as well? How do we want to handle it for homebrew that involves more than a single thing (like Rituals or Spellshaping)?
7) What are the rewards?
I'll volunteer something from the Ritual system for the first contest.
1) I'd be willing to help. Note: I am only an "ok" optimizer.
2) I agree with others who say this should be a separate forum.
3) I think judging criteria should be fixed before entry guidelines. Unfortunately, some homebrew is targeted towards lower levels, where other homebrew (mystic theurge fix) is usually targeted towards higher levels. I'd tend to think benchmarks of a build at 7th and 14th level are reasonable.
4) I think: Flavor, Exposing Broken-ness, full use of the homebrew being used, & optimization. Also, I don't think the author should be a judge ... make it more impartial.
5) Mid-contest edits --> I'd say that anyone who finds some broken-ness or lack of clarity should get a small bonus when being judged, but that the material should change mid-contest. So that people share their discovery's as they go, and the author is free to update if desired.
6) I'd argue that what is being optimized is _very_ important. If it is too small (optimize 1 feat) then the competition doesn't have much meaning, and if it is too big (optimize Frank & K in their entirety) then it may take too much time for people to read and become familiar. I'd argue that this should be 1 class + a few supporting details (feats, custom skills, whatever). And if it is more, than this, it not be in scope for the 1st competition.
7) I think this is partly dependent on what mod's can do. At the very least, bragging rights!
I think item 6 is very important ... finding the right scope, as well as homebrew that is in some sense comparable will be a tough job. I'd almost say that the judging committee should approve any submitted homebrew, so that it can all stay very vaguely comparable.
For example, how would you compare a spell point system with a mystic theurge feat?