Jay "saurik" Freeman has been hard at work on what he calls a "full package index:" a centralized database of Cydia packages. One of the first features based on this fundamental restructuring is now live on Cydia's homepage: the new " Manage Account" option. Finally, there's a simple way to determine what you've purchased on the Cydia Store, giving you a quick and easy way to re-install your apps, tweaks, and themes after a restore.
There are some caveats to be aware of. First off, if you had originally purchased your package through RockYourPhone, it may or may not show up in your "Installable Purchases" list unless you've explicitly linked the two accounts. As saurik says, he "tried very hard to automatically connect together accounts 'as if by magic' sometimes you will need to manually associate your Rock account."