I always love the highlander secret santa, it's actually the only fic exchange I've participated in ever (done it for the last 3 years). Though I have done other challenges both in highlander and other fandoms. I think for quite a lot of people it's the only highlander fic they write some years (I've been very unproductive in 2011).

Would be lovely if there were more popular exchanges for highlander, but I suppose it's a question of getting the momentum behind it . I find these a lot of work (writing fic doesn't just flow for me) but if there were some other spaced out....