I am chock full of ideas, and always out of time.
Why doesn't somebody create a stock market + product trading platform?
Think eTrade + eBay!
Basically just add in an auction platform to mtgox.
You could start out selling only video cards since that is what the bitcoin community really wants right now and expand from there.
If buyers didn't have any bitcoins to bid, they can purchase them through the stock market.
If sellers want to cash out, they can have money wired to their bank accounts just like paypal.
Most importantly, buyers and sellers can create a feedback record of their credibility like on eBay.
It would kill two birds with one stone by creating demand for bitcoins (since you will need to bid/buy with bitcoins) and adding liquidity to the bitcoin markets.