For those of you who aren't familiar with them, a commander deck is a 100-card deck led by a commander (legendary creature card, or planeswalker). All non-basic land cards in a commander deck may only appear once and may only cost magic colors that appear on your commander.
For instance, if you used Aurelia, the Warleader as your commander, your deck would be comprised of Red and White cards only.
Commander games are typically meant to take a bit longer, and possibly be played as 1v1 or free-for-all, and each person starts with 40 instead of the standard 20 life.
So, if you do, or have played Commander, what deck(s) have you constructed? What strategies did you employ?