Love it or hate it UML is important for anyone involved (Architect/Developer/Whoever) – either you need to create designs based on UML and you need to understand that someone else has. Sure it has its challenges and for some specific things there are better solutions (DSL's – more on that some other day). I am "old school" and over the years have used Rational Rose (or whatever IBM has renamed it to since buying Rational out).
But as are aware Rational tools are very pricey and I was on the look out for something reasonable. Most people have heard of EA (no, not the game company) which is a decent tool and not too expensive (at least the Desktop edition).
Of course if you are stingy like me and want something completely free then check out StarUML which is an open source UML/MDA platform and is pretty decent. When you work with it enough you will find some annoying things – most of which has workarounds. There are one or two things it just cannot do, but I only have been using it for a few months now and am quite impressed. Is it better than the likes of EA or Rose, nope but it is pretty damn good for the price.