Drm free help (ga inside)

Any of those work. But not everything from Humble is DRM Free. Keep an eye out for that.

Also the Fireflower Games site. Gamersgate has a selection of DRM free games, but you need to dig in to find those.

Added ga

Wrote a long reply but it got swallowed by the system :(
Short version: you can also check Groupees and itch.io, or even Steam (some games actually come as DRM-free copies when you download them).

GOG

Piracy aside,
You can get some DRM free games from groupees bundles or itch.io, not sure on desura.

other

GOG. Though GOG will not stop you they ask you not give to play your copy of game to some one else.

i voted humble because it is the only one i brought on
but it seems thaht gog is the winneer
i should take time to consider their offer =)
Thanks folks
have a nice day

BUMP (I voted Humble Bundle)

Indie Game Stand has a nice selection of free games.

It looks like you want to install on multiple computers, however the manner in which you want to do it would actually be against GOGs terms

I'm running the computer lab at a camp...

Are you planning on installing the games on each of the computers in the lab? Just a word of caution, unless you are planning on buying separate licenses for each install, it would probably be illegal to just purchase one license to put on multiple machines -- particularly bad if you are planning on doing it in an official capacity at a job or other organized environment and basically teaching the kids that piracy is ok. It would open up the organization/company to potential lawsuits or other hazards.

You may want to get in touch with the publishers of the games you are interested in and they might have some sort of volume licensing deal, or possibly discounts / freebies for educational groups. You should also talk to the camp managerial staff or lab purchasing department about software budgets as they should be the ones paying for the software on the computers. If you talk to the right PR person, they might see that having their games played by a bunch of impressionable kids could lead to future sales.

GOG is the best probably, but Humble Bundle has many portable versions of the DRM-free ones, so you don't even need to install them. (A little more difficult for some company sniffer programs to detect. :D)

GOG

Real gamers buy original :D

EDIT: Haven't used HB.

GOG for sure, i don't know any better site for drm free game

You cant go wrong with Gog :)