Windows/Mac/Linux (Firefox): QuickDrag won't look terribly new to fans of previously-posted extensions Drag de Go or Super DragAndGo, but it's a lighter-weight extension that does similar work. Grab a swatch of text and drag it up to your address or tab bar to perform a search on the term. Grab an image and drop it above to open it in a new frame, or save it Mac-style to your desktop. It also makes non-clickable URLs easy to open by (you guessed it) dragging them into an empty tab space as well. QuickDrag is a free download, works wherever Firefox (including 3) does.