Here at New Internationalist we have been using Redmine for our task management for about 4 months now, courtesy of a fantastic hosted service called HostedRedmine which is provided as an ad-supported service by BitBot software.
Using some sort of ticketing system is critical when you are dealing with a large, complex and varied workload. The New Internationalist web group had previously been using trac, which is also a great piece of software (you can even integrate it with Vim). However, use of trac had gradually tailed off in favour of a simple Googldoc of shared tasks, and personal lists for our own work. For my own workload I'd started with toodledo, but then moved to mGSD, meaning that I was able to keep on top of my tasks quite well in a GTD stylee but that it was hard to report on progress to others, or to alocate tasks within the software.
This year we came to the conclusion that we needed something to organize our workload better. Using a hosted service was attractive because we wanted to make sure we were happy with the way the system worked before committing to it. HostedRedmine was especially attractive as it offers a database export, when we either want to host our own Redmine instance or pay for another service to host for us.
The Redmine software itself is a very nice ticketing system, similar to trac. Where it shines is for managing multiple projects, something which trac never quite managed as nicely as it should have. This has proved rather useful in helping us to avoid the frighteningly inbox like list of tickets that can sometimes confront one when usng a ticketing system, and we hope will allw us to do things like have days when we focus on marketing work or on IT infrastructure. The UI is also nice and straightforward without too much extra fluff.
My experience so far has been pretty positive, I've felt like we've missed fewer tasks and that we have managed to track our time much better than we've managaed to do before. I would like Redmine to have some sort of caldav integration so that I could get reminders when deadlines were due. I have yet to try out vim-redmine, but will no doubt gie that a shot in the next weeks. Watch this space.
The next stage of the roll out will be to get other members of the co-op using the system to report bugs and track our progress. We may well migrate to a paid service or self-host in order to set up remote git hosting. Redmine integrates very nicely with git, which is our revision control system of choice.