This may be old news, and the offer will expire quickly, but from now until May 6th the "Everyday Math Apps" sponsored by the McGraw-Hill School Education Group are free to download for teacher appreciation week.
The link to the iTunes page is here:
http://itunes.apple.com/WebObjects/MZStore.woa/wa/viewArtistSeeAll?dkId=11&ids=413312889&softwareType=iPhone
