Merriam-Webster Lookup Button.

[Dan2]

For all you fellow word freaks. This handy little button will give you the definition of any highlighted word by pressing a button on the toolbar.:)

http://www.m-w.com/button/

[Slice]

Thats tight! Thanks for the hook up.

[Death Engineer]

<gives Dan2 the award of the year>

[MR. SLiK]

firefox has an extension like that without the toolbar. It's very handy.