Source: eGrabber Newsletters

Here is a simple search script that will allow you to aggregate the job postings from a specific company across various job sites.

"Company Name" site:indeed.com OR site:simplyhired.com OR site:jobster.com OR site:careerbuilder.com OR site:dice.com OR site:monster.com OR site:hotjobs.yahoo.com OR site:careerjet.com OR intitle:jobs OR intitle:job

For example, if you are looking job postings from IBM, the search string will be

"IBM" site:indeed.com OR site:simplyhired.com OR site:jobster.com OR site:careerbuilder.com OR site:dice.com OR site:monster.com OR site:hotjobs.yahoo.com OR site:careerjet.com OR intitle:jobs OR intitle:job

The search results will display job postings from all the above sources. You can customize the search preferences to display only recent results.