There are many gaming sites that are designed to help gamers beat the unbeatable.  A few of the most popular ones will be touched upon here.  Also, below are a few intro videos and tutorials. 

Bandai Namco: This is the official Katamari Bandai Namco forum website community.  All questions can be answered on this forum as well as hints and tips.  Also it wouldn't help to check out the Katamari official website. 

Gamespot: This site not only gives reviews on Katamari but it also have demo videos, images, news, and quick links to other media.  It is also frequently updated and is always buzzing.

IGN: IGN is another notorious gaming website that is alway updated and has plenty of forums for support.  On the IGN cheats pages you can find cheats and codes to unlocking special items in the game, forums, walkthroughs, reviews and blogs.

GameFAQS: GameFAQS is owned by Gamespot but has some different information.  Its specialty is FAQs and walkthroughs.  It also has a pretty extensive discussion board to ask people for help.

Cheat Genius: This site is set up mostly like a question forum.  Someone posts a question to which people reply.  It also contains eastereggs, unlockables, and hidden items in its repertoire.  

Cheat Masters: Another site with easy to find cheat codes for getting hidden items.