Are there any sites where you can upload-download large files (for free) as to exchange them with other guys?
Thank you

How large? With gmail you get 3GB for free... so you could share the account with someone and do it that way.

Here are some other options to check out: http://www.google.com/search?num=100&hl=en&lr=&safe=off&q=free+online+file+storage&btnG=Search

You're best bet would probably be something like Rapidshare (http://rapidshare.de/)

If you are going to be doing this regularly, maybe something like DropSend (http://www.dropsend.com/pricingsignup.php) would be more appropriate. There is a free version or for as little as $5 you get more transfers etc.

I've used www.yousendit.com (http://www.yousendit.com) before.

You can also transfer large files via MSN. Sometimes when I need to transfer a 4.5 GB file, I use MSN. It takes about 26 hours, but I find it is easier than chopping the file up into many smaller pieces.