Thank you for the lovely OneWire library, it works well!
The only problem I had with it is that it really eats up SRAM. The CRC tables use about 256 bytes of RAM (from the 1 kbytes the atmega168 has).
On my system I have temporarily commented out that section, but I think a good solution would be to use PROGMEM for the CRC tables. (Some links about PROGMEM:
http://www.avrfreaks.net/index.php?name=PNphpBB2&file=viewtopic&t=38003
http://tinker.it/now/2007/03/04/avr-and-of-course-arduino-ram-limits-overcome/
PROGMEM - Arduino Reference )