A very large list of many challenge sites. There you can also post your opinion of our site!

The best page ever! If you wanne learn something about buffer overflows and UNIX (things that we are not able to offer at the moment) then you should check out this site!

Very good german/english site with lots of good challenges, a forum, a messaging system and tutorials. You can choose the language between English and German.

Nice challenge site with some really nice challenges I have never seen before!

Good site with many hard challenges. One of the best sites i have seen! (from Caesum)

Very good site with not so easy challenges!

Challenge site

Site with many articles about programming stuff and a collection of logical challenges.

Small challenge site with a handful of easy challenges. They'll probably add more soon.

Challenge site of MiB's. What else do I have to say. Check it out!!! :-)

Coding, Logic, Stegano, Crypto and Realistic Challenges

Recently relaunched with great layout. There are no challenges yet, but some articles and a forum.

A site of programming challenges, which you can solve on your own machine. You hand in only the solutions. Hence you can use any programming language you like, or some math and brain on the first levels.

Programming challenges of past contests and regularly new online contests.

The training portal for the USA's team for the international olympiad in informatics is open for everyone and a good introduction into solving algorithmic problems. The contests are available under http://ace.delos.com/ioigate.

A very good german forum about nearly everything! (programming, security, hacking, math, logic, ...)

Really good tutorials! I like the fingerprinting ones (part I and II) most.

good security site.

One of the biggest database of exploits and vulnerabilities. (bugtraq)

A security site maybe not as big as securityfocus but with more details about the exploits.

A nice, big exploit collection.

Some nice Ollydbg tutorials for beginners written by DeathSpawn.

Word-list collection!

The World Wide Web Security FAQ

If you do not know how to use google or you think you might know everything about it, check out this site!

Collection of real good whitepapers! You have to check them out.

Security & Hacking Information (daily update)

Daily updated security portal with exploits, advisories and the largest collection of tools and texts you may ever need. Introducing more than 10 different security related sections. Make us a visite and you wont regret.

Exploits, papers, shellcodes and videos. Useful database!

All (?) RFC-documents, reachable through a nice search-engine.

The ultimate online version of all help files and SDKs ever made by microsoft!