http://www.mediamolecule.com/

Official website of Media Molecule, developers of LittleBigPlanet.

Contains up-to-date information on news and DLC releases. 

http://blog.us.playstation.com/

Official News Blog for Playstation 3, including LittleBigPlanet related news from Sony. 

http://forums.littlebigworkshop.com/lbp/

This very forum, don't need me to explain the benefits of this particular link.

http://forums.littlebigworkshop.com/lbp/board/message?board.id=pod&thread.id=63530 

This thread contains a list of links to all the most useful and helpful threads in this forum.
Definitely worth checking out.

http://forums.littlebigworkshop.com/lbp/search?advanced=true

Sorely underused search engine for this forum.
Use this and you'll might find that your LittleBigPlanet query has been asked before.

http://news.littlebigworkshop.com/en-us/category/LittleBigChallenge.aspx

Want to keep up-to-date with the latest LittleBigChallenges?
Then this is the link for you. 

http://community.eu.playstation.com/playstationeu/?category.id=c_EN_LBP

Official European LittleBigPlanet forums, post here if you're looking to talk to European players that don't always post here.

http://www.mediamolecule.com/?feed=podcast

Media Molecule's podcast feed for when you want to hear the latest news and updates straight from the Molecule's mouth.

http://www.mediamolecule.com/tag/mmpicks/
"Mm Picks", Media Molecule's hand picked levels reviewed.

http://twitter.com/Media_Molecule
Media Molecule's official Twitter account.

http://www.facebook.com/mediamolecule

Media Molecule's official Facebook profile.

http://twitter.com/Mm_sackgirl
Twitter account of a Media Molecule developer, was previously the official Media Molecule Twitter account.

http://www.flickr.com/photos/mediamolecule/

Media Molecule's official Flickr profile, look here for all sorts of images posted by the Molecule's including screenshots, renders, event photos and any other general photography of their activities.

http://www.youtube.com/mediamolecule

Media Molecule's official YouTube profile.

http://mediamolecule.blip.tv/ 

Media Molecule's official blip.tv profile, check out this site to see all their video releases, including the popular MmPicks, Tips Specials and other Molecule related video recordings.

http://mediamolecule.blip.tv/rss

Video podcast for Media Molecule's blip.tv videos.

http://www.jp.playstation.com/scej/title/lbp/main.html

Official Japanese website for LittleBigPlanet, who have on occassion, released news about upcoming DLC before it was announced here, normally due to the time difference.
So if you're looking for a sneak peek of upcoming content, it's sometimes worth checking out.

http://www.youtube.com/user/LittleBigPlanet
Official LittleBigPlanet YouTube page for North America.

http://www.youtube.com/user/LittleBigPlanetUK

Official LittleBigPlanet YouTube page for the UK.

http://www.youtube.com/user/preshaa

YouTube page belonging to a Media Molecule developer, look here for all the videos relating to the "Mm Picks", levels picked out by Media Molecule themselves as being that little bit extra special.

http://www.facebook.com/profile.php?id=1415463869

Sackboy's very own official Facebook profile.

http://itunes.apple.com/WebObjects/MZStore.woa/wa/viewAlbum?id=297301033&s=143444

http://www.amazon.com/Little-BIG-Music-Oddities-Inspired/dp/B0025WC7NO/ref=pd_bbs_1?ie=UTF8&s=dmusic&qid=1241262147&sr=8-1

http://www.amazon.co.uk/Little-BIG-Music-Oddities-Inspired/dp/B0025N5302/
Like the LittleBigPlanet soundtrack?
Then these links are for you, you can purchase the official LittleBigMusic MP3 album at iTunes, Amazon.com or Amazon.co.uk, whichever is your preference.

LittleBigMusic is an album which contains all the Daniel Pemberton tracks from the game, along with some new music that was inspired by LittleBigPlanet.