You can never have enough buttons for games! Ground Branch - my current tactical shooter - is a particular case in point, it has a *lot* of key bindings.
Having said that, I like to use a compact side gaming keypad - the Orbweaver - instead of my full sized keyboard. I like everything just a fingertip away and don't like to lift my hands from my controllers to activate an obscure key-press. The down-side of this arrangement is that I always seem to be just one key short of what I need!
To remedy this I have just bought a Footswitch controller, which is exactly what you might think it is...
Essentially, it's a one button USB switch which is programable via an associated piece of software. Simple.
The key I am (always) short of is my voice chat button, I have been using my mouse's side buttons to activate the in-game comms or my Teamspeak but I now what to use these buttons for some game actions. So I resorted to a foot switch for comms and it seems to be a excellent choice and I wonder why I haven't tried one before.
As I said, it comes with it's own software so you can map a button or macro to the switch...
You can get two or three switch versions of this foot switch, but I stuck with a single one as I don't want to get my foot confused - jabbing at the right button under my desk! After I have got used to this one I *may* upgrade, we'll see.
One thing to note is the tension of the switch, I did worry I would activate this switch accidentally with my foot resting on the switch, but it is sprung so that you have to exert a certain amount of deliberate pressure to click it. You can actually rest your foot on the switch without clicking the button.
All in all, a simple but very useful addition to my gaming setup!
> Docooler PCsensor USB Single Foot Switch Control One Key Customized Computer Keyboard Action Pedal - £17.99 from Amazon.co.uk