Hello, I'm Etlase2, and I am tackling this problem. One way to ensure transactions remain fairly honest is to charge a percentage fee rather than a flat fee or a fee based only on bytes/coin age. This is possible when you use an account ledger system instead of a transaction ledger. For this and a million other details, click the link in my sig.
that's quite a read; do you have a cliff notes version?
i'll try to digest it over the md weekend -- look forward to discussing