Yes! In the "Personal Toolbar Folder" section of your bookmarks, add a link to this:

javascript:q=document.getSelection();for(i=0;i<frames.length;i++){q=frames[i].document.getSelection();if(q)break;}if(!q)void(q=prompt('freshmeat search:',''));if(q)location.href='http://freshmeat.net/search/?q='+escape(q)

This will create a button which, when clicked, will cause a text box to pop up in which you can enter your search.