My phone (and I suppose most) has a set of speed dial numbers (9) . The ability to dial these via button presses from the headset would be quite useful. Perhaps 3 presses for speed dial one, 4 for speed dial 2, etc or something like that? It probably becomes impractical for speed dial 9 (11 presses) but the ability to dial other than the last dialed number would be very useful.
Ability to dial speed dial numbers