Token Tips adds a list of items that you can purchase with a token to the tooltip. The items you already own are highlighted in the tooltip as well as the location of the vendor you would turn it in to.
Token Tips currently adds tooltip information for the Tier 4-14 Raid Tokens. Tier 9 has only partial inclusion as of r4. All remaining tokens will be added for the first release.
To have Token Tips report items you own that are in your character's Void Storage, please go and visit your Void Storage. Token Tips will monitor your Void Storage inventory once accessed.
Bugs and Support
Did you find a bug? Do you have a feature that you would like to see added to Token Tips? If so, you can submit them here: http://www.wowace.com/addons/tokentips/tickets/