Psyco is a Python extension module which can massively speed up the execution of any Python code.
Many readers will have heard about Arjan van de Ven and Auke Kok's work to boot an ASUS Eee 901 in 5 seconds. Inspired by this work, and because I have the same laptop, I decided to try to reproduce their results. So far I have not come very close to their 5 seconds, but I have made some significant improvements compared to the default boot time for Debian on that machine; this article describes what I've done.