I use an addon called "nuke anything" that lets you right click and remove pretty much anything (only until the page is reloaded). It's a lifesaver when you browse with JS disabled since that can cause pages to display poorly (menus spewed all over the screen for example) but it comes in handy a lot for sticky elements. I have seen a few sites that manage to prevent certain things from being selected though. It's nice to have yet another tool to fall back on if I need it.