That's a nice suggestion NMJH, but it really doesn't transfer ownership of the apps.
I've been wondering about this question myself. Someday Apple may provide for this kind of transaction, but there's nothing available to us now.
It used to be that if your hard drive crashed and you lost all your purchased music you had one oportunity from the support staff at Apple to re-download all songs that were still available on the store at no charge. That was a one-time deal only and now Apple lets you re-download all your purchased music yourself as many times as you want, as long as the device is assigned to your Apple ID.
It may be just a matter of time before Apple allows for the combining of Apple IDs which would allow people who have purchased downloads from iTunes with multiple Apple IDs to combine all those purchases into a single account. It could also help people like me who have one Apple ID for purchasing stuff and a mobile me Apple ID that just has iCloud data to combine those accounts into a single Apple ID. If that utility ever materializes that could be used to transfer the purchases like the OP asked. In my opinion, Apple is more likely to focus on the combining of accounts than it is to provide a solution for the transfer of purchases.