...so we put a jet on your jet made out of jets so it could have a jet...
Had this idea when I first got Blackbird back in February since I thought it could use a jet pack, but waited until now to actually try it. Cybertron Wing Sabre fits over the shoulders well enough (as it does on so many figures... really, try it!). With a bit of cutting and modding, I could make it a really secure connection, but... there's absolutely no chance of it standing without support, so I'll refrain from cutting up Wing Sabre.
But I do like the ridiculousness of it.
EDIT: click the thumbnail for the full-res picture. Stupid photobucket...