Not the best of photos, but heres a few oddballs out of my toolbox;

The black handled ones have got me out of a number of awkward situations, albeit often at the expense of damaging the nut. They do grip pretty much anything though, provided it fits in the jaws, and are better quality than their appearance suggests.
King Dick is self explanatory, but the Cromna is my favourite; It's just a shame that I've only got the one size. It grips most things, and also acts as a ratchet open ender. The little hemispherical boat tilts to allow the jaws to sit square, whatever sized nut you use it on.
The missle dumpy one is ex-Uboat WW2 vintage, with a set of captive shims to vary the size.