Shopping for video games this holiday season? The Entertainment Software Rating Board (ESRB) is helping parents make better buying decisions with a free app for your iPhone or iPod touch.

The ESRB rates video games based on content and assigns a letter value – E for Everyone, T for Teen, M for Mature – with content descriptors telling you what you’re likely to find in the game (depictions of blood and gore, for example, or alcohol or drug use). Those ratings are printed on the box itself, to help provide parents with a better sense of what’s in the games they’re considering for their kids.

While those ratings can give you a general idea of what’s in the game, sometimes a more in-depth description is necessary. The ESRB application includes rating summaries for games published since July, 2008. A search engine is included to help you find specific titles.

If you’re not using an iPhone but your mobile device has Web surfing capabilities, the ESRB has also set up a mobile Web site with the same content.

(A tip of the hat to Matt Peckham at PC World for making us aware of this app.)