The following was posted by Bill in reply to a topic in Requests and Suggestions but I think a reply deserves to be in Tips and Tricks:
I’ve been using this now for a week and it works brilliantly. Anyone who has more than one database and has QuicKeys 3 installed will be able to make even better use of it.
First of all, always ensure that Show Groups has been selected in Tools. Then set up a QuicKey using “Open Items” for each of your databases. I have two - Work and Private. My QuicKey assigned to Work is control-1 and my QuicKey for Private is control-2. These allow me to swiftly move back and forth between my two databases without visiting the pull-down menu File>Open Recent… And with my list of groups positioned on the right of the screen, I can drag anything I like straight into the correct group (or folder) of the correct database rather than using the cumbersome process of using the Services menu (which only clips to one designated folder anyway). The Groups Panel changes to that of the active database so using QuicKeys it becomes an absolute breeze to get information into the right group of the right database.
There’s another way to do this. I use Quicksilver to change between databases. I predefined some shortcut keys for my four databases and I swich between them by invoking Quicksilver and typing the shortcut.