I'd like something that can produce pretty diagrams out of the box for software, business processes, etc for showing to clients. Anything free would be a bonus too. Any advice?
None of these earns the bonus for being free, but perhaps you could take a closer look:
* Microsoft Visio - I've never actually used it, but it used to be the de facto standard back in the old days when nobody ever got fired for buying anything Microsoft :)
* http://lovelycharts.com/ - this is an online diagramming app built on the Flash platform (I can't help mentioning that :), very cool stuff. However, I've never used it for anything but the simplest diagrams, I suggest that you try it yourself.
Based upon my experience:
Open Office Draw is quite good. For greater power, you could consider InkScape. Dia is also good if you have the time to tweak to your requirements. I end up using OO-Draw for 80% of my diagrams and it interfaces with OO-Impress.
omnigraffle comes to my mind, you can use pencil maybe, try balsamiq and the like....
mindmaps is another thats very generic in nature and has got gr8 utility.
* Microsoft Visio - I've never actually used it, but it used to be the de facto standard back in the old days when nobody ever got fired for buying anything Microsoft :)
* http://lovelycharts.com/ - this is an online diagramming app built on the Flash platform (I can't help mentioning that :), very cool stuff. However, I've never used it for anything but the simplest diagrams, I suggest that you try it yourself.