Googol Deskbar provides you with quick search over major search engines and on-line services. Select the word and search from any application by pressing Ctl+Alt+G. Or choose engine you want to search by pressing Ctrl+G for Google, Ctrl+Y for Yahoo etc.

There is more. With multiple deskbar layouts you can use it as:
Webmaster tool: work with your web-site
Web 2.0 search: search Web 2.0 web-sites
Network tool: ping, nslookup, whois etc
SEO tool: improve your SE rankning
Developer tool: search manuals, forums
Local search: switch to local search engines. French, Dutch etc.