AVR-Chat

Juistb discoverd this chip, an 18 pin DIP (also available in SMD 
packaging) which provides a very powerful FPU + other functions, 
including 2 12 bit ADCs, a full RS-232 port (including level shifting), 
string processing, NMEA string parsing, numeric to string and string to 
numeric as well as numeric format conversions (8, 16, 32 bit int back 
and forth, as well as IEEE 754 FP back and forth).   Costs are $19.95 
qty 1 (Sparkfun), $13.95 qty 100. 

http://www.micromegacorp.com/umfpu-v3.html  fior technical information.

  Offers both SPI (15 Mhz) and I2C (400 Khz) interface, ~~ 30 Mhz 
operation (without ANY external components, you can add an external 
crystal/cap network to boost speed a little, apparently).

   Not exactly inexpensive, but not badly priced for all it will do.

   Thought you guys would like to know about this, in case you didn't 
already know.

avrFreak