Put this in your ~/.bashrc to automatically adjust the number of processes make creates. This snippet is licensed under the beerware license.

# ----------------------------------------------------------------------------
# "THE BEER-WARE LICENSE" (Revision 42):
# < marko haapala at aktagon com > wrote this file. As long as you retain this notice you
# can do whatever you want with this stuff. If we meet some day, and you think
# this stuff is worth it, you can buy me a beer in return.
# ----------------------------------------------------------------------------
alias make="make -j$(cat /proc/cpuinfo |grep processor | wc -l)"