Google acquired Picasa recently, signaling their entry into digital photo storage. Google's systems are designed to store large amounts of data across their cluster, so this business seems like a nice fit for them.
John Battelle speculates that travel will be next, but I have my doubts. The travel business is nasty, requiring interfacing with complicated legacy systems like the SABRE database. It's not clear to me that Google has any expertise or competitive advantage in this area.