This is part of a regular series of posts on search experience updates that runs on Fridays. Look for the label "This week in search" and subscribe to the series. - Ed.

The week leading up to Halloween has brought a flood of new treats for you.

Music Search
On Wednesday, we rolled out our new music search feature, fully integrated into Google's web search. Now, when you search for a band, singer, song name, or album title, Google will recognize it and return a special music result on the top of the page. These new special music results do exactly what you want - they let you listen to the full song. To provide this feature, we have partnered with Lala and MySpace (formerly iLike) to bring you full-song streaming. That's not all, however. The real "wow" in this new music feature is that you can type in phrases of lyrics, we recognize the song - and bring you the song for full play. You can listen, verify it's the one you were looking for, and then continue on to buy the song on iMeem, iLike, Lala, Pandora, or Rhapsody.

Example searches (singers): Lady GagaTaylor SwiftJay-ZJack JohnsonMichael Jackson
Example searches (band): ColdplayTV on the RadioThe KillersMGMTThe Rolling Stones
Example searches (song): Sample in a JarWaiting for the World to ChangeWhen Doves CryAll I Want for Christmas is YouWalking on Sunshine
Example searches (album): Dark Side of the MoonAchtung BabyAqualungEvil Urges
Example searches (lyrics): gonna be a good night tonightcan feel the hand of fatelucky we're in love in every waytake away this ball and chain

Social Search
On Monday, we introduced Social Search on Google Labs and Google Experimental. Social Search finds relevant content that your social circle has published and returns that content with your web search results. What defines your social circle? To use Social Search, you need to be logged in to your Google Account and opted in to the Social Search experiment. We then analyze your Gmail contacts (if you have a Gmail account) and the connections on your social networks (if you have a Google Profile and have listed public social networks like Twitter and FriendFeed). What kind of results do we find? Our Social Search results include blogs, photo albums, web pages, and reviews. This way, you not only seeing the most relevant content on the web globally, but you also see the content most relevant and personal to you.

To try Google Social Search, go to Google Experimental and click the "Join the experiment" button pertaining to social search. Then try searching on Google for something your friends may have written about. Example searches like 'restaurant' or 'vacation' tend to occur in people's personal writings. Social Search results always occur at the bottom of the page, so scroll to the end of the page to see these results. You can also trigger Social Search results explicitly by opening the Search Options panel and clicking on 'Social'. This will cause all of your results to be from your social circle.

Similar Images on Image Search
In addition to our new features on core web search this week, we introduced a new and revolutionary way to refine image searches to our main image search functionality this week. The feature is called "Similar Images". We've had it for a while as a separate site, but it has proved so useful and interesting that we decided to make it part of our core image search. The idea here is to find an image that you like and then click the "Find similar images" link below it. This may seem simple, but think about all the complicated things you can express. For example, if I wanted a picture of a single turtle swimming, and I wanted the turtle to be headed to the left rather than the right, it would be almost impossible to express as a keyword search. Now with "Similar Images" features, I can simply do an image search for turtles, then find an image that meets my requirements, like the seventh image on that results page, and by clicking the "Find similar images" underneath it, I get a page composed of solo turtles actively swimming.

Example search: jack-o-lanterns, then click on "Find similar images" under the fifth image to get jack-o-lanterns lit from within in night-time settings
Example search: birthday hat, then click on "Find similar images" under the second image to get multi-colored birthday hats
Example search: peacock, then select "Find similar images" on the third image to get white peacocks with their feathers displayed

Personalized Search on Mobile
This week we also introduced personalized search for the mobile phone. Personalized search has been available on our website for some time. Now, when you are logged in on your phone, you get the same personalized search results on your mobile phone as well.

Google Suggest now global
Internationally, we also rolled out Google Suggest on our search results pages. Now, the helpful suggestions that you see when you begin typing on our homepage and results page are available on 156 country domains and in 52 more languages.

And to wish you a Happy Halloween, trick-or-treat us by visiting the homepage ( today and clicking on the Google logo.

Hope you enjoyed this week's features. Stay tuned for what's next!