They're called Open Search Plugins because they use the Open Search Specification, not because they're Open Source. I'm not trying to be a dick or anything haha, but I learned how to create these through reverse engineering after looking at the Demonoid Search bar which used the old system, then I looked at some docs, compared existing examples, etc. Besides, the plugin IS the source *hint hint*. If you guys have any requests just let me know, and if you want me to change anything on any of these let me know as well. I'm using all of these myself..
If any of you have any requests, if you want me to write one for a particular site, just let me know in the comments!
For the clueless: Click on a link to install.
Urban Dictionary Search: Search the Urban Dictionary for a specific term or phrase.
Ultimate-Guitar Tab Search: Search Ultimate-Guitar for Tabs to a particular song
Acronym Finder Search: Search for the definition of an acronym
Ubuntu Wiki Search: Search the Ubuntu Wiki
Digg Search: Finally an easy way to search Digg
W3Schools Search: Search W3Schools, the ultimate web programming reference
Flickr Search: Search Flickr 
Metacritic Search: Search Metacritic for reviews on many things
Guitar Center Search: Search Guitar Center for various music related products for further information and reviews
Newegg Search: Search Newegg for all types of electronic products for further information and reviews
I have created more at SearchPlugins.Net. View them here!
Brought to you because the stock search plugins SUCK (Except for the Wikipedia one)
Great article! We added it to our website as a useful tool for finding torrents!
http://filesharefreak.com/bittorrent/bittorrent_opensearch.html
(Give us a couple hours to update it!)
—Sharky (Admin)
Glad you liked it. I added one for FileShareFreak, which seems like a nice site which I’ve never heard of before. However, for some reason the icon doesn’t show up in the search provider, but it does on the site.
Hey bro…
Can you add the ability to select a category to search in for the Demonoid plugin?
Which one.
Umm, I don’t understand the question… :/
The Demonoid one…
Right now, it pulls results from ALL categories on Demonoid.
It would be great if you could add the option of selecting which category to search in.
I’m guessing we’d need a second form field/dropdown with the different categories listed in it.
Some thing like:
All
Anime
Applications
Audio Books
You know, all the different categories on Demonoid…
I asked ‘which one’, as in, which category…what’s so hard to understand? Yes you can do that, but you would have to add different plugins for different categories. That’s why I’m asking which one in particular.
All of them…
You can’t add some kind of drop down list that you can select a category from?
No, that’s not possible.