If you find yourself with an excess of stone, you are clearly not playing DF like it is intended to be played... Or at least, how almost everyone here does it.
One word: Megaprojects.
You'd be surprised at how much stone a single megaproject takes up. I am working on what I call the "God Dam", in my current project. It'll take over 6,000 raw obsidian to build, can house as many as a hundred dwarves, and can provide approximately 5,000 power via waterwheel. Dimensions are 37x10x7, and thus far has taken almost five in-game years to build.
It's probably also best to keep one or two (i've got four) masons on hand making stone blocks full time.
Generally, I order batches of about 1,000 at a time, and set them to low priority, then if I need other masonry done, I just create the order, and slap a higher priority on them. (Not to mention the fact that I've got four other Dwarves on constant masonry (construction) duty, and I've still only got about 25 residents...) That may be because I've let most of my migrants get slaughtered by those bastard goblins that showed up in year 2, and forced me to lock the gates... I've never opened them again, actually... No need for wood, and I locked my fortress off from the surface completely, so really, it's no big deal... Maybe it will become a big deal when I have to fight them off with no access to weaponry, and no anvil, but I think I might try to lure them onto the dam, and then drop them in the river...
Anyway, like others said, the atom-smashing bridge, lava, blocks and bins, or just grinding out masonry are all good options. The real Dwarf's only answer, however, is to build something for the glory of almighty Armok. Something big, something impressive, and more than likely, completely useless is the best choice.