The Job Search Engines below will search multiple career sites and job boards simultaneously.  Generally, you can perform searches by job title, key word and location.

Beaucoup

BrassRing.com - Search over a million high tech jobs from the web's top career sites.

CareerBuilder

CareerCity.com 

CareerShop

JobBank USA

JobDirect.com -  (students must register)   

JobFACTORY- JobSpider

The Job-Search-Engine 

The Job-Search-Engine

MSN Careers

Wanted Jobs 2k