If you already have Sky+ then you are pointing at 28.2 degrees East so can only get signals from any co-located satellites at this location (other than Astra 2A-D, the only one is Eurobird1) provided you manually enter the frequency etc. in the "manual tuning" menu on your Sky box. With a fixed dish installation like Sky you are limited to this satellite "cluster" though.
You can find details of all the channels available at 28.2E here;
http://www.lyngsat.com/28east.html
There isn't much there that isn't English I'm afraid. If you get a multi LNB or motorised set-up you could look at other satellites listed on www.lyngsat.com, but with Sky equipment you will only access digital signals not any of the analog ones
The old Astra 1F-L analog "cluster " at 19.2E has loads of stuff on, some of it free to air (unencrypted) but some is encrypted still. You won't get these signals with a Sky or Sky+ box though but would need a more sophisticated receiver capable of receiving both analog and digital signals and dealing with different video decryption standards.
http://www.lyngsat.com/astra19.html