Open source project management tool?

I need some project management software. I'm not fussed about compatibility with MS Project. Something that works on windows and os x would be nice. Any recommendations?

I tried looking for just such a tool a while ago without success (but also without much effort).
A quick googling for 'free project manager software' got several interesting links, but I can't do any recommending.

Perhaps this comparison at wikipedia would be a start-
http://en.wikipedia.org/wiki/List_of_project_management_software
Just having a list of names is a good thing to start with.

Sorry I can't help more than that- I'm sure you've already googled it yourself.

edit:
This guy seems to feel strongly about a couple freeware options.

If you just want basic Gantt charts there are a few like ...

planner ( http://live.gnome.org/Planner ) - seems to have stalled
GanttProject ( http://ganttproject.biz/ )

... not listed there.

But that wiki page looks good to start.

I looked for ages for something with more than just gantt charts including proper time tracking. I never found anything suitable (that was free/open source). I got somewhat forced out of that position so it's not my problem anymore. We now use nothing which works extremely well </sarcasm>

Good luck

What do you need it for? Timeboxing and estimates? Or do you actually need Gantt charts and all that jazz?

We've given up on using MS Project to do project management (for software development) and we're currently evaluating a couple of different (though not free or open source) web-based task tracking systems.

The company I'm at used to use Project, and had gantt charts coming out the wazoo. Useless as tits on a bull, since none of them were ever accurate, and we were always behind schedule. Our department has shifted to the Agile/scrum stuff. You can get software to run the scrum process, but the low-tech method is just index cards tacked to the wall, which, I have to say, I'm really digging.

Yes, it's timeboxing that I'm after. The guys in the IT departments in the other areas of the company use MS Project. But I'm a difficult bastard that wants to use my linux desktop at work and my mac at home.

I'm not super keen for an web based solution, OpenProj looks worth a try, it's a Java app. I'll also try project.net which is a web one.

Both seem to now be commercial but there are Open Source/Community versions of both it seems.

I didn't mean externally-hosted. We self-host the stuff we use, but I can understand that this might be a pain as well. Mind you, if you're sharing the info, you've got to put it somewhere...

We're currently evaluating TargetProcess, which seems pretty good for agile/scrum stuff, but maybe not so good for what you're doing.

For personal projects, I use Trac (which appears to be down right now), and I'm liking it. It lacks certain features, but there's a pretty good plugin community, so it's getting better (I'm particularly pleased that someone's writing a Visual Studio plugin for it). Again, it's a bit software-development-focused, so may not be a good match for what you're doing.