The following values are supported:

0 – No randomization. Everything is static.
1 – Conservative randomization. Shared libraries, stack, mmap(), VDSO and heap are randomized.
2 – Full randomization. In addition to elements listed in the previous point, memory managed through brk() is also randomized.

The /proc/sys/kernel/randomize_va_space interface controls ASLR system-wide.

If you don't want a system-wide change, use ADDR_NO_RANDOMIZE personality to temporarily disable ASLR. Controlling this personality flag can be done with setarch and its -R option (manpage), prepending a command.
I find it really convenient to open a completely new shell using:

setarch `uname -m` -R /bin/bash

This will open a new Bash shell for you with ASLR disabled, including all child processes (programs run from this shell).
Just exit the shell once you're done.