sites for cheap attractions ? (Munich)

Hi guys, my name is Patrice and I've been living in London for 2 months. I'm a student (originally from Germany) and taking an internship at the moment. Living in London is great but quite expensive as well. I have already visited many attractions, but they're all too expensive !! :-/

I have already searched for discounts at the internet and I found Protected content . I think it's pretty cool, you can get a discount Protected content of each attraction or restaurant. The only thing you need to do is to print out the voucher. And there are some attractions in Germany as well :-)
Do you know, if there are similar websites for famous big cities like Munich where I can get discounts for attractions ? Cause I'm planning to move to Munich after my time in London...

I'm looking forward to hear from you !! :-)

Cheers!
Patrice