Hey I've been running my campaign for nearly three years now and I've been using the same soundtracks for two of them.  I'm hoping some one out there can give me some new peices to use.

I would prefer soundtracks so longs without lyrics. 

Video game or movie soundtracks are prefereble and any recomendations would be great!

Here are some pieces I've found really nice.

The Priates of the carribean sountrack works well for ground battles and boarding actions:  http://www.youtube.com/watch?v=npWSI9iu2i0  (for just general sailing around)

When in port and making aquisitions or at the start of a promising endevor I use the Windwaker sound track to give the game a more light hearted feel.

http://www.youtube.com/watch?v=pOFyH5g_XJk

Space battles obviously need battlestar galacticca: http://www.youtube.com/watch?v=vogXU33BO30&playnext=1&list=PL11D7B1EE7C6EBD5E&feature=results_main

And for exploring alien ruins or just setting off into the unkown I find the Halo soundtracks work very well:  http://www.youtube.com/watch?v=Z5eobV_zyrc

Silence is good for really tense social interactions.

http://new.fantasyflightgames.com/edge_foros_discusion.asp?efid=123&efcid=46&efidt=181170

http://new.fantasyflightgames.com/edge_foros_discusion.asp?efid=159&efcid=46&efidt=592901

http://www.fantasyflightgames.com/edge_foros_discusion.asp?efid=159&efcid=46&efidt=494189

Enjoy

Bear McCreary is a god of sci-fi soundtracks so Battlestar Galactica is a must have, but he has also done the Caprica spin-off series soundtrack which is a bit more mellow and the Terminator: Sarah Connor Chronicles soundtrack which is pretty cool too.

If you want something a bit more dystopian then i quite rate the Neo-Tokyo soundtrack http://neotokyohq.com/music.html

And lately i've been using the Mass Effect soundtracks also. 
 

Between those 5 sources (BSG, Caprica, T:TSCC, N-T and ME) you have multiple days running time of soundtracks to work with so shouldn't get stale in your campaigns.

Final note - have something prepared for Cantina style encounters that isn't the Star Wars cantina music - it may be funny but it realy detracts from the setting.