This is me testing the viability of the forums.
I've been continuously bugging Rat/Ratzy/Soldier? about this for (probably) months.
You really need to have a mic to communicate effectively, and if we're playing in ladders we'll quickly be at a disadvantage if we can't communicate as effectively as our opponents. It doesn't need to be anything flash (EB games is selling plantronics (sp?) ones for $15 at the moment which is a bit of a steal), but it needs to work or you will have wasted your money...slightly. If we don't all have them we're going to be slower at getting information across, as we can only type when we're safe or risk getting killed when we stop to type "sniper on the right" in the middle of a firefight.
So yeah, I suggest that we need to get mics, so get one if you haven't already.
(As an aside, the worthy investment of a mic can assist you outside of TF2 and other multiplayer games with stupid little projects like this. Brilliant)