codesmell.org

can be found here and creates images like this:

fun to use and good results, at least for simple sequence diagrams: http://www.websequencediagrams.com/

If you happen to have the need to draw a few simple, good-looking UML diagrams, your choices are few. Either you turn to something commercial, overly bloated with things you currently don’t need, or you end up with hardly working, crappy looking and hard to work with Java tools. Yes, there is a middle ground, [...]