Happy Halloween! For the special day, most of the search engines and portals have special logos or themes on their home pages.
In fact, Google's logo was carved and filmed at Google and that made up what you see as the Google Logo for Halloween in 2011. Note, one of the pumpkins was 1,298 pounds!
Plus, Google's dressed up the Google Webmaster Help forums and AdSense Forums.
Google's Video Halloween Logo:
Google also has a static logo:

Bing Halloween Theme (video step 1):

Bing Halloween Theme (video step 2):

Yahoo Animated:
Ask.com:

Dogpile:

AdSense Forum Halloween Treat:

Google Webmaster Help Forum Halloween Treat:

Our theme here at the Search Engine Roundtable:

For the past year's special Halloween logos see the 2010, 2009, 2008, 2007, 2006, 2005 and 2004 Halloween logos.
Forum discussion at Google Blogoscoped Forums and Google Webmaster Help.

Comments:
Zaitbahajji
10/31/2011 01:25 pm
Love your theme by the way!! Just a question though : did you put the Tombstone that reads "RIP" on purpose next to BING and Yahoo ! tabs :)
Barry Schwartz
10/31/2011 01:27 pm
No, my designer did that without thinking about it. Pretty crazy, no?
Bill
11/01/2011 01:58 am
Happy Halloween everybody! I love these Halloween logos! I especially enjoy the animated logos like Yahoo's Halloween logo. AOL use to have animated logo's to, but not any more. I have a collection of these Holiday logos. After nearly 3 years, I finally located AOL's animated Thanksgiving logo of 2008. The static version was listed on Search Engine Roundtable Nov 27, 2008 "Happy Thanksgiving '08 From The Search Industry." I have the animated version of the photo shown there. I will post it closer to Thanksgiving!