Practically all of the Bluetooth add-ons come with the serial port profile (SPP), some specialized ones come with the A2DP (audio) profile.

However, what I think would be great would be implementing the HID (Humane Interface Device) profile.  This would give us the ability to interface with a lot more consumer devices "out of the box" by utilizing their pre-existing HID implementations.  e.g. you could have your TD (tiny duino) talk to your smartphone (smartphones implement HID but don't, in general, implement SPP).

I don't know if such a BT chipset exists - but something with a bunch of selectable profiles would, of course, be even cooler (but I don't know if it's possible)

p.s. I want to make a small chording keyboard for use with my smartphone.

p.p.s. received my TD stuff earlier this week :-)   haven't had chance to play with it yet :-(