If you bike long enough you might be able to charge you cell phone while traveling to work. Motorola showed off a docking station that uses an old school dynomo to charge a phone.
https://aving.net/usa/news/default.asp?mode=read&c_num=33918&C_Code=01&SP_Num=53
The bike and charger are targeted at people who need communications but are not connected to the electric grid.