A small list of Ubiquity commands that I daily use:
tiny: to quickly create a tinyURL
g: to show the results of a search on google
And more after the jump!
search: start search
get-lyrics: to search for song lyrics
add: to add an event to your google calendar
twitter: to update the status on twitter
ebay: to search for an item on ebay
email (text) (to contact): to send an email directly from Ubiquity
get email: to see how we are logged in Gmail
restart: restarts firefox
map: Google Maps
weather: see the weather for a location
fore: to see the weather forecast
email this to: to send via mail any selection from a page
Zoom: to zoom the page
open book: to open a bookmark
Wayback: to view the old versions of a site
view source: to view the source code of a page
youtube: search for videos on youtube
define: to search for the meaning of a term
highlight: yellow highlight for a selected text
herd: to access the herd and look for new commands
tab: to move to another open tab
digg: to digg a page on digg.com