Lately I've been dreaming of getting an Arduino this summer. With 14 digital I/O pins and 6 analog pins. Aside from all of the flashing LED possibilities, one thing I've been dreaming about is using the I2C bus.
I2C is a two wire interface which allows me to connect multiple slave devices to a host, only using up two of the analog pins on the Arduino. The number of slave devices is limited, I2C only has a 7 bit (127) address space, and most devices only let you select 2 or 3 bits worth of its address. Thus you can only have 4 EEPROMs on one bus, and only 8 different temperature probes, but that obviously doesn't bother me very much, I'm still going to have fun.
I've requested a 256kb (32kB) and a 1Mb (125kB) EEPROM free sample from Atmel. We will finally see if what they say about getting free chips from manufactures is true. The Arduino does come with 512 bytes of ROM already, but adding another 125kB sure expands the possibilities.
One thing that has been bothering me is that I've looked around online, but I haven't found any projects using anything other than EEPROM over I2C. Are there any other chips other than 24Cx EEPROMs that are fun to use with a microcontroller over I2C?
Edit: I have found some DS1721 temperature probes, and requested two of them from Maxim. Obviously one of the first projects I'm going to attempt is going to be taking a temperature reading, logging it in my oodles of EEPROM (125kB + 32kB + 512B onboard), then plugging it into my computer and dumping it all.
Edit: Let me be very very clear. Atmel has completely ignored my sample requests, which is rather irritating. Oh well.