In no particular order:
i) Place a bid/buy now button at the bottom of the auction listing, along with shipping information, etc... just a quick overview so that anyone who does actually read the description doesn't have to bother looking for 'top' or scroll all the way back up. It annoyed me when ebay removed this.
ii) Must partner with shipping companies or postage label printing companies. In the US, these include stamps.com, endicia.com, shiprush.com. If you don't want to open the API to users, at least let some partners have access and create apps. Time = Money and it's a PITA to transfer addresses one at a time into other programs.
iii) Partner with a cashback site to draw visitors to the site. I know mrrebates.com pays for referrals, so why not have a promotion with them to offer maybe 2-3% cashback on ebid purchases and make money from advertising them on the front page and earning referrals? Obviously make a rule that listings can not have referrals in them?
iv) Have an option so that the first picture doesn't appear before the auction description for those that know how to put pictures in their own description.
I'm sure there are plenty more things I could come up with, but that will do for now I'm gonna try and start selling on here, but really need things to become less time consuming.