Mostly, I run a few companies and it would help me a lot responding others the same. I've wanted finding way to do this. 
How about the just your name.
This is a great app - and I think will do exactly what you want
http://itunes.apple.com/us/app/email-signature-pro/id317243351?mt=8
That looks really well. Seems like people are complaining about some fixes possible on the app store reviews. I'd really need it working perfect on my iPad. I email on it a lot too.
I honestly haven't read the reviews. I've had the app since it was launched (got a free promo code here on MR) and haven't had any issues. I'm not a power user and haven't used all the potential for the app. But even at 4.99 it's worth a shot.
Not saying this about you. But there's a weird perception issue in the marketplace (app store) of what is and is what is not expensive.
People should look at Apps for what they are. If I can get more functionality out of my phone for $5 I don't see that as expensive. People complain when apps are anything but .99 but really. Is less than the price of lunch so bad to part with for something that might make your life easier?
Sorry to "rant" and this was NOT meant to be aimed at you. Just a general commentary on people's buying behavior/perception.
I've been using my name, but having the company showing is a bit more pro looking, I think.
That helps a lot. Thank you. I'll try it.