That's the $64k question :) There seem to be a fair number of local people/shops that will do this for you (usually advertised as "we'll sell your stuff on eBay for you!"), but they take a really hefty cut, so much so that it usually isn't worth it for me to haul all my 'stuff' over to them... I'm hoping that a larger automated system like shyp would be able to reduce the seller cut to something more reasonable :)
Yeah, the eBay drop centers aren't a very good deal. As you mentioned, you have to take your stuff to them, and then they might not accept it. Most won't take anything under $50 in value, or anything over a certain size. Then they do very little effort in determining the right price, instead opting for no reserve auctions with really low starting bids. Then they keep 50% commission on average. So their value prop is essentially: bring us your stuff, we'll take some of it, sell it for less than it's worth, and then keep half of that.
I think creating a business that resold on Amazon would be smarter. It's less work, easier to price, and the customers there are willing to pay more than on eBay. You would be limited to only taking items that Amazon has in their system though. I was going to work on this (actually selling on a combo of Amazon/Craigslist/eBay), but I had the most hellacious back and forth string of emails and phone calls with Amazon's tech support only to confirm that they require $500/year developer fees for the privilege of developing software that works with their marketplace web services api. And unlike Apple where you only have to start paying once you wish to deploy an app into their app store, with Amazon you have to pay while developing the app too.