Google SMS.

Google SMS is a handy tool — just send your query as an SMS message to 46645 (“GOOGL” on the phone keypad), and within a few seconds you’ll get an SMS or two with the answer. I tested this a few months ago and found it worked pretty well for queries like “price 20GB ipod,” “pizza 94401,” and “define haberdasher.” Looks like they’ve been adding some features since then: You can now use Google’s calculator function (“sqrt(-4)”), get weather reports (“weather san mateo ca”), and even get driving directions (“from sfo to 1 market st san francisco ca”). Amazing. Here’s a wallet sized tip sheet (PDF).