Living in a world where technology has evolved in service of our business and personal needs, you'd think brands would understand that changing ad copy over the holidays would be beneficial to their brand perceptions. It surprises me how far pay per click marketing still has to come to be regarded as a profession; right now, it seems like it's still chock full of half-baked attempts by offline marketing managers interested in "that internet thing".
As simplistic as the process of ad scheduling (dayparting for you old school types) is, it seems to have escaped a number of retailers this year. In the spirit of the holidays, I'd like to offer a very quick and easy way to ensure that 2009 is the year you start looking like a rockstar to your board.
Step 1: Create two campaigns - one for pre-holidays and one for after. This is especially important if your business is expecting to put on a Boxing Day or January Sale.
Step 2: Create a list of keywords and copy them across both campaigns so that your keyword inventory is identical. This only makes sense if you don't have any seasonal-specific keywords (we'll get to sale keywords later); don't copy "Christmas Turkeys" over into your post-holiday campaign - chances are the people that are searching for that keyword might be looking for something else.
Step 3: Write some ad copy. Keep it relevant to the season - Christmas Special: Socks on Sale, Guaranteed in Time for Christmas is great for your pre-holiday searchers, but make sure you create an equally relevant ad for your post-holiday traffic. Something along the lines of 20% Off All Socks - Boxing Day/January Special! usually works a treat.
Step 4: In "Edit Campaign Settings", opt in to ad scheduling (i.e. turn it on!):

Step 5: If you've never turned Ad Scheduling on before, you'll have to specify your time zone. For single time zone countries like the UK, it's relatively easy. For US and Canadian marketers, make sure you select the right time zone for your business (if you have a physical location in Houston, it makes zero sense to set your time zone to pander to Yankees on the East Coast; make sure you set it to Central). Setting up different campaigns for different time zones is another post altogether, so we'll keep it relatively simple. Remember - you cannot change your time zone once it's been set. Make sure you don't accidentally set it to Tapei (GMT +8); it can get a tad confusing.
Step 6: Christmas Day was on a Thursday this year, so you can set your ads to go off

without interrupting your turkey conquest plans. Name the time you need your pre-holiday campaign to go off, and it'll go off. Then, all you need to do is make sure that you do the same for your post-holiday campaign - except this time you schedule a time to turn it on.
This is a pretty simple way to protect your brand reputation online. For instance, I'd be very unlikely to purchase something from the retailer at the top of this post, just because they haven't shown me that they care about their products or their brands enough. I know it's not advanced PPC techniques, and there are a load of programs out there that can switch on and off by specified date - this is just a ridiculously simple, band-aid fix to make sure you look like you want your customers' business post-holidays, even if you're still sipping mojitos in Varadero.