An update of mines!: >>.bashrc:
This is a drop-out replacement for cd:
0) pd DIR == cd DIR (plus push to the shell's dir stack, plus store DIR as LAST_DIR)
1) pd == pop a dir from the stack (the shell's BACK button)
1.1) if none, pd LAST_DIR (useful for new shell sessions after pd DIR or pd . in an old one)
p.s. Thanks to Vitaly@astrails for the idea on improvement.