shameless plug, but check out our startup http://sellsimple.com - we're tackling the same problem.
One of the things that most appealed about Sold is that they send you a box, you put the thing in it, and that's it. For me, that's the biggest pain point.
Is that something you're looking to do?
Instead of sending a box, we automatically purchase a shipping label for your item using the shipment method of your choice (USPS, UPS, FedEx). The shipping label already has the address of the buyer and everything filled out.
All you need to do is drop off the package (we'll show you the closest shipping locations).
From there we automatically track the package and show both the buyer & seller realtime updates of the package location & delivery.
We're calling this service "ShipSimple" and it's bundled into the overarching SellSimple platform.
The ShipSimple feature will be released in version 1.4 (coming very soon).
US only I guess?