I hope I'm not out of line here, but I figured I'd share this with all of you here in case there's any interest. I know there are a few available chips for this stuff here already, and they're probably as good or better than what I've been cooking together. But in the interest of learning, and because it's a lot of fun, I wanted to make my own.
http://www.sabrotone.com/?p=3992 - source code, some schematics and a basic PDF with info.
I wanted an 8-pin DIP AVR chip that I can integrate into some of my favorite effects to make them a bit more useful. I also wanted to make it controllable by an external chip.
http://www.sabrotone.com/?p=4004 - tap-tempo tremolo, schematic and vero layout.
http://www.sabrotone.com/?p=4031 - tap-tempo phaser, schematic and vero layout.
Right now I have a tremolo and a phaser that I can control using a central tap unit (same chip), but I'm aiming to extend the feature set of the central controller and also add tap-tempo delay. Goal is to have a single tempo unit on the pedal board that can supply base tempo to all relevant effects.
Hope I'm making sense. Tell me if I'm not.