//reddit or //python.o — the .com is automatically added; .o becomes .org and .n becomes .net
United States// — avoids the handy wikipedia redirect, instead searching Google for United States
Proposterous//define — scrapes Urban Dictionary for the definition(s) of proposterous.
New York//map — Google Maps search for New York. New York//img is an Google Image search.
require//code;l=ruby — Searches for ruby code containing the term require on GitHub.
Die Bruecke//translate — Translates using Google's Language detection to english. Optionally, you can put in a to language but this will assume you are translating from English. You can add a from language after the to language so the query would be "Die Bruecke//translate|en|de" or "The Bridge//translate|de".
google.com//archive — visit the Wayback Machine's archive pages for google.com. Don't put in http:// it'll break :)
1149//rfc — visit an RFC through IETF tool's nice HTML series.
/r/whatever — visit the subreddit /r/whatever on reddit.com