It's not a single touch, but we just released our new app Sign, which is a gesture-based speed dialer. You press once to activate the recognition engine and then simply draw a gesture ("sign") right from the home screen. It might be slightly slower than a single tap, but not much slower. However, it prevents misdials and inadvertent calls which can happen with direct dialers.
Also, it lets you choose between calling and texting.
The signs are completely customizable so you can make any sign you want for a contact, i.e., numbers, initials, drawings, etc. because it allows for multi-stroke gestures.
If you want to try it, there is a free version, Sign Lite, which has a limit of 3 contacts. The full version ($1.99) allows for an unlimited amount of contacts.
Just search "Sign" in the market. Check it out and let us know what you think.
Here's a video demo:
[video=youtube;2QsyXtqVAEw]http://www.youtube.com/watch?v=2QsyXtqVAEw"]YouTube[/video]
Here are some screenshots:
The contact list with assigned gestures
A single stroke Sign on the homescreen (half cut off)
A multi-stroke Sign on the homescreen
Multiple gestures within one Sign (although this would defeat the purpose of a "speed" dial, it is possible to have up to 8 strokes in any Sign)
Call confirmation
The settings screen
Contact Assignment Screen