is a set of lookup interfaces useful for patent attorneys and agents.
6 Nov. 2012: Looks like the USPTO's MPEP has been redesigned. The google search has been updated to work with the redesign. Cheers!

MPEP search via Google:

Browse MPEP - MPEP Index

Patent Lookup (PDF) via

Patent Lookup (text) via USPTO:

Application Lookup (text) via USPTO:
example: 20010000044

Inquiries to: admin (at) mpepsearch (dot) org