AdWords rules, and so can you! - Inside AdWords
From their blog post:
With automated rules, you're able to create rules to automate bid, budget, and status changes on a specific part of your account (selected keywords, ad groups, campaigns, and ads) that are triggered at a particular time. For example, automated rules could be created to perform the following tasks:
- Enable ads promoting a special offer late on a Sunday night when the offer goes live
- Automatically raise your bid to the first page CPC for all keywords in a campaign that contain the word 'sale'
- Generate more traffic on your peak shopping days by automatically increasing your daily budget on Mondays and decreasing it on Wednesdays