Recently I have been using Cellar Tracker, which is an online wine inventory tool. Overall, I am very pleased with this tool. One of the best things about this tool is that it is free. They do however, prominately request donations. That seems fair though for a rather useful and well written tool.
Some things do not seem to be yet implemented (or at least not entirely) community fetures (public sharing of cellar data), integration into E-Robert Parker and more. It does however, currently include some level of barcode support; though I have not used that yet.
One improvement I would like to see made is with how storage locations are managed. I enjoy the freeform nature of the storage locations; however, I would prefer to have an interface just for managing storage locations and place location and bin limits to force accurate inventory records.