Geek biases

Matthew is wondering how to remind himself of ideas that emerge out of its fruitful brain in mobile situations (such as in the bus or on his bike).

Two answers for you, Matthew :

the geek answer : buy a PDA like the cool Sony Cli� (yes, I have one) or a PDA-like phone like the Motorola A388 or the SonyEricsson P800 (no, I don't have one)
the non-geek answer : use, ahem... a paper and a pen ! It's always ready for use, and smaller and lighter than any electronic device you'll be able to find ;-)