How can I do a non-A/R cash receipt?

If you need to receive cash but don't want it to hit the receivables account, use the miscellaneous distribution feature on the Cash Receipt screen. Use a generic customer to begin (e.g., CASH). Once you've entered the amount, go to the Misc. Distributions tab. Enter a distribution for the full receipt amount, specifying an alternate account for the distribution. This will by-pass the usual receivables account, using the alternate account instead.