I'm sure you've seen how Google change their logo for special occasions – in fact most days they have something going on.
This is easy for Google to keep up as they have a dedicated team of people researching and designing new logos!
With a bit of cleverness you can achieve some special with themed backgrounds, logos and other graphic widgets that change based on calendar dates.
Your site always looks fresh, up-to-date and relevant to your customers.
The Cooks Kitchen have Christmas hats, snowflakes and snow drifts at Christmas, then hearts and cupcakes for Valentines Day. They've even got a different logo for pancake day!
Why not add a little bit of seasonal variation to your site?