With the ability to create custom applications in PmPC, it might be worth having the ability to share them with other PmPC users. I would envision something like a "recipe" for the custom app that would be shared (not the actual binaries). For example, the app "Desktop Info" is not supported for PmPC. If I created a custom app and was able to share it, then others needing this app could download the recipe and create their own.
You'd need to somehow keep the bad actors from posting bad things. But this might be community based with a voting/comment system so customers would (hopefully) effectively vet the recipe. For example, if multiple people created a custom app for "Desktop Info", I could review the ratings/votes and comments for each and then download the recipe that best fits my scenario.