i don't know how to slow things down on the i2c bus -- there doesn't appear to be support in the Wire library for that. as for the amount of code -- that's the whole system and i didn't have time to break out the parts. the slave code (slaverman.pde) is actually the most interesting, since it allows the slave to behave like any good synchronous query-and-respond i2c slave (such as the Ds1307 real time clock).