One general concept we've been playing around with is one that Green Reaper came up with awhile back. The idea is that people could submit skins and allow others to submit additional pieces to those skins and themes.
Example:
Someone uploads a WindowBlinds skin but it doesn't support some of the new WB4 features like shellstyles and such.
So another user could submit an addition to it that just has those features.
Then usres could choose to download either the main skin alone or the skin entotal.
Now, implementing something like this wouldn't be trivial but we were interested in hearing ideas on how such a system could be implemented that provided a balance to protect skin authors while not making it so difficult to do that no one would actually make use of such a feature.