I believe many people here will enjoy this website:

[voyagerOne]

http://www.projecteuler.net/

Many interesting and challenging programming problems...

Bill

http://www.mytopcoder.com/gmol

[JuLieN]

http://www.projecteuler.net/

Many interesting and challenging programming problems...

Bill

http://www.mytopcoder.com/gmol

Doesn't look so interesting to me

Could not connect to MySQL

[voyagerOne]

Could not connect to MySQL

ummmm...errrr....That's the first problem you need to solve!

Out of all the time the site works it goes down when I share it...

[JuLieN]

Could not connect to MySQL

ummmm...errrr....That's the first problem you need to solve!

[Edmund]

you can use google cache for the time being:
http://webcache.googleusercontent.com/s ... roblem%3D1
replace the last "1" by any number below or equal 382

[JuLieN]

The website is now working again, and you're right, it has many interesting problems. Some look very simple and other very tricky.

[voyagerOne]

Problem 185 is personally one of my favorite...

See if you can solve it.

[jshriver]

http://www.projecteuler.net/
Many interesting and challenging programming problems...
http://www.mytopcoder.com/gmol

Yup fun site, remember using some of them as practice problems when prepping for ACM competitions.

The ACM website does (or at least use to) publish their own interesting problem sets geared for programming as well.