Used KeywordSelection for Windows?
The Download Now link will prompt a local download of the Firefox extension. To install the extension directly, open the file using your Firefox browser.
Developer’s Description
By Nrlz
Extend the functionality of keyword-searches so that they can be activated with the mouse. Simply select some text in your current window and then click on a keyword-enabled bookmark. A search will be performed with the text selection. If no text is selected, it will open the bookmark like a normal bookmark.
This also works inside Web forms. If you are typing some text inside a text box, you can select some text and click on a keyword-enabled bookmark to search that text. This version is the first release on CNET Download.com.
Explore More

Mozilla Labs: Rainbow
FreephraSEarch
Trial versionDave's Quick Search Deskbar
Free
Louisiana Personal Property Bill of Sale
Trial versionDistrict of Columbia Lease Agreement
FreeExtension List Dumper
FreeChildrin R Skary
FreeMyShoppingGenie
FreeOdd Math Out
FreeGraph Your Inbox
FreeThe Exploit Database
Free
Domain Name Dominator
Trial version