I need to find a way to have the multiple choice options in a Google form change based on a set of cells in a Google Spreadsheet that is constantly changing. Any ideas?
The functionality you are requesting doesn't currently exist. A feature request around linking Google's forms to spreadsheets would be your best bet to keep the two in sync.
There is always the option to create a form using URL parameters as outlined here: https://docs.google.com/support/bin/answer.py?hl=en&answer=160000