I've posted several dozen auctions with Garage Sale now, and I've run into nary a hang. It works "out of the box" and integrates nicely with iPhoto and the iSight camera for posting auction images. Garage Sale even includes a Dashboard widget for tracking the status of your auctions at a glance.

This is exactly the kind of seamless integration and fluid user experience that made me switch to the Mac.

My only complaint would be that the end of auction tools seem to require manual updating -- they don't automatically detect when you've paid, shipped, etc. It's a minor gripe, but they would be much more useful if they were integrated with ebay's status tracking rather than running as parallel duplicates.