Most of my friends already know this, just making it public I have been working on an open source project lately it is called JALDS (java algorithms and datastructures) it is a repo of reusable algorithms and datastructures. I see a lot of similar packages in C ( most notable LEDA ) but not in Java so this is my attempt to build one. Check it out at http://code.google.com/p/jalds/ its all in svn and uses maven.