Here are the commands I've created:
Translates a word from English to Arabic using the open source Qamoose dictionary.
Example: eng2ar anything
will give you the translation for the word 'anything'.
Searches for books in the Online Books Page (http://onlinebooks.library.upenn.edu) by words in the title. If you wish to search by author, use the Yubnub command freebook-author.
Example: freebook beagle
Example: freebook voyage beagle
These searches return "The Voyage of the Beagle" by Charles Darwin.
Searches the Online Books Page (http://onlinebooks.library.upenn.edu) by author name.
Example: freebook-author darwin
Example: freebook-author charles darwin
Searches the National Library of Singapore catalogue by keyword.
Example: nlb harry potter
Other EXTREMELY COOL commands (that I've come across so far) are:
g - searches Google.
gs - searches Google Scholar.
shrink - TinyURL, but I'll probably stick to my regular bookmarklet most of the time for this. You can find it on the TinyURL main page if you scroll down a little.
gmaps - Google Maps.
map - Multimap.
am - searches Amazon.
tr - Google Translate. Use it like this: tr en fr friend to translate 'friend' from English to French. Other languages: simplified Chinese zh-CN, German de, Italian it, Japanese ja, Korean ko, Portuguese pt, Spanish es.
thes - thesaurus.com search
say - text-to-speech. (Cor blimey!)
acro - look up the definition of an acronym.
answer - Answers.com
Three cheers for Yubnub. I think I'll be using it a lot.
Why nlb doesn't work:
Yubnub automatically inserts a + between two or more search terms. So "nlb harry potter" gets the URL <> which is incorrect. You want "_harry%20potter" at the end instead. The search will still return results, but it will think it's searching for the word "harry" only.
I've no idea how to fix this, but I emailed the site's creator, Jonathan Aquino, about it, to see if he can fix this. I suppose you could try using the catalogue available through elibraryhub, maybe that would work.
UPDATE: nlb does work. Jon specially implemented a new syntax that transforms spaces into, well, spaces (%20) rather than into plus signs. And the NLB catalogue is immortalised on the yubnub website as the exemplar for this syntax. Jon was also kind enough to credit me for "suggesting" this fix, but it was his idea, I just supplied the problem!