Open the Carbonite "Guide" by either middle clicking the Carbonite minimap icon, or by clicking on the question mark icon (if you hover it with your mouse, the tool tip will say "-Guide-") on the Carbonite map toolbar. Then click on the "Visited Vendor" heading in the left panel of the "Guide" window. After doing that, you will get a list of vendors you have visited in the right panel.
Unfortunately, it only currently works for vendors that you have previously visited. The bright spot about that, though, is that if you click the "? >>" in the list, you will get a list of vendors by name, and any that are able to repair will be listed as such. IE: Alexis Walker >> (Repair)
Clicking on the name will also give you a list of items that you can purchase from them.
Ahhhh, the vagueries of the aging mind. Wait.... What was I saying?