My first exposure to Banks was The Wasp Factory, which remains one of the only books that has ever literally nauseated me. It was excellent, but it's been hard for me to pick up another book of his since.

Oh, actually I did read The Business, which introduced me to the delightful question "how do you count to 1000 on your fingers?" (without using 'intermediate storage' like keeping track of 10's in your head). I still use that when teaching elementary number theory.