Suggestions:
Set up a website - possibly a new forum - where users advertisements, like on bitcointalk.org, would go mainly to a fund designed to pay devs. In additon to Gavin, there could be 1 or 2 more full time/part time devs if possible. Then there could also be a list of features that are wanted, and there could be bounties for these. Either these tasks could be assigned to someone proving to have the necessary skills and be paid pr. mini project, or people could compete and if their contribution were accepted, it would be included.
Bitcointalk.org forum have collected a shitload of funds, and have already assigned a software firm with the task of developing new software for the forum to a rather costly price.
Perhaps some of the forum funds could be directed towards bitcoin development?
Another suggestion:
I'm not sure if it would be a good idea to force an extra fee on all or some transactions to fund bitcoin development, I'm sure most would reject that. But what about having another foundation (!) or atleast some way of managing bitcoin payments and rewards to developers, perhaps by making a fund that regularily pays out to devs and for bounties and the way it would receive money would be from mining pools, exchanges and other willing bitcoin services, that would be willing to pay say 0.1 to 0.3% of their profit towards such a fund.
After all, this would benefit everybody, as devs would have more incentive to work with the bitcoin software development, and that would then benefit the contributors as they would be able to run their services on top of a better system that's more scaleable, more secure, and overall better.
Then another discussion would have to take place as how to mange and distribute those funds. But before that's even discussed, it would need to be established that this is something the community wants.
I would not object to some devs working on bitcoin actually taking painstakingly measures to stay anonymous, to stay under the radar so to speak - so if there was a concerted attack or compromise on devs, at least some devs would be remaining.
I'm sure there are many skilled people who could contribute code, but for most people they also need to make money, so not everybody can work for free, at least not full time.
Also if a model like the one described above came to fruition, it would be important to do the outmost to ensure that there would be no main special interests or corruption in that arrangement. I do also think that bitcoin services contributing could all have a small graphic on their site, explaining that they contribute to the bitcoin project, which would be a good thing to have.
For example: "Official Bitcoin project contributor".
Because we have the block chain, then all devs could have their btc address published, so it would be easy for anyone to follow the bitcoins and ensure they was used for the predetermined causes.