You can use it for freesat. When you get the sky+ installed the engineer will make sure your dish is capable of sending 4 signals out. 2 will be used by the sky+ which leaves 2 free.
All you need to do is run another cable from the dish to whichever room you want the freesat in, and plug the old box in. Hey presto, free digital channels for another room (but not all the super-duper sky channels unless you pay them a multi-room subscription.)
Bung the sky man a few quid and he might even do it for you.