If you liked the post on lawn mower chopper bikes, you'll love these DIY bicycle hacks.
You gotta love the Railbike for riding abandoned train tracks. You'll have to make sure that they're abandoned, though, or start riding like Lance Armstrong.
For practicality, the Shopping Cart bike is a winner, it just needs a kiddy seat in the back.
For flash, the JCycle Nightrider lights up the night.
The Soul Cycle pumps up the volume with custom built sound system.
And, just for the fun of it, the Golden Gate Bridge Bike is mobile whimsical art. Maybe this will inspire you. Happy hacking!