Theres the SRD

http://www.d20srd.org/indexes/monsters.htm

though you would have to go through the pages and extract the stats. Some of the DM helper tools...err um DMGenie and err whatever other ones there are have a lot of their stats as XML blocks which ought to make extraction pretty simple. Dont ask me about licensing tho - I never quite got the details about the two free licenses but the SRD is free to rip and use in certain ways.

BTW you can link these SRD pages to the monster icons in my app with a little web hot link - pretty useful if your the DM.