backing tracks

Does someone know where I can get backing tracks?

On this website. At the main page look for a 'jam' button.

but where can I get some "real" backing tracks?

I'm not quite sure what you mean.

If you do a search on www.google.com for "backing tracks", you'll get a plethora of results.

Also try the search function of this board, might be able to find some there.

You need to explain what you mean by backing tracks.
Midi? Karoake? Copyrighted songs? Something to play scales to? Instrumentals? Loops? Samples?

instrumentals, no solo's

The only person on this site I know for sure of who does instrumentals is Schmange. He usually posts several different versions of tricks like the solo, solo to music then just the music.
If you mean instrumentals of copyrighted songs though, you'll probably have to buy them. And in that case it'll be marketed for a specific purpose like Karoake.

The problem with posting copyrighted songs on the internet is the amount of money it costs people to post them. I've done several of my own things like old Beatles instrumentals but there's no way I'd ever put them on the internet. I tried asking at the Harry Fox Agency once how much it would cost to put an instrumental of Every Breath by the Police on my old web site and they basically quoted me in the thousands of dollars range for the rights to use it.
Even then they couldn't give me an accurate cost because the amount you pay is dependant on how many people are going to download it.

So with all that said, you'l probably have the best luck just using Google to search for words like Karoake, Instrumental rock or whatever and then decide whether it's worth it to buy a professionally made instrumental, or get one done by probably an amateur musician posting it illegally on the internet.
You can also keep an eye out in the usenet newsgroups like alt.binaries.sounds.----- and filter for the word 'instrumental'.