Here's something very high on the cool scale. The retro-cool Moshi Moshi 01 handset (MM01) can be used with mobile phones, VoIP via USB and yes, iPhones and iPads.
Old-timers like me remember back when talking on the phone meant standing next to the wall, tethered (physically, not Bluetooth) to a hunk of plastic and metal, speaking into a bulky handset that hung from a 2- or 3-foot length of cord. The folks at Native Union have brought the sexy back with the MM01. When fitted with the proper adapter, the MM01 can connect to most mobile phones including the iPhone.
Additionally, you can connect it to an iPad (again, with the proper adapter) to use with VoIP apps like Skype. It's like having a telephone at the end of a cookie sheet! Who wouldn't want that?
Seriously, we think this thing is great. For $US29.99, you get the handset and 3.5mm connector jack. Other adapters are sold separately.