Monstrous Regiment - Sir Terry Pratchett - Bog

The Monstrous Regiment in question is made up of a vampire (reformed and off the blood, thank you), a troll, Igor (who is only too happy to sew you a new leg if you aren't too particular about previous ownership), a collection of misfits and a young woman discovers that a pair of socks shoved down her pants is a good way to open up doors.