This is probably a bit of overkill for my bicycle, but on a motorcycle the EXO 900 is the king of versatility. It can quickly flip from a full face helmet to a flip front modular to a 3/4 helmet.
Other features include an EverClear No-Fog faceshield and an anti-scratch retractable SpeedView sun visor. Truth be told, this certainly isn't the first modular helmet out there. However, at $270-$280 the Scorpion would be far cheaper than something like BMW's System 6—although the latter has advanced noise canceling features and integrated Bluetooth. [Scorpion via Jalopnik]