Auntie supposes we'll all learn on Monday about Apple's new streaming service iCloud, as MobileMe's happy blue iDisk cloud gets all steel-ified and Apple starts making use of its massive North Carolina data storage megaplex.
But yes, there are other solutions. Matt Gallagher's StreamToMe lets you send music stored on your Mac or PC to a remote iPad, iPhone, or iPod touch. Supported formats include MP4, MP3, AAC, and WMA.
Your system must be set up to be remotely accessible, and you need to install a special application called ServeToMe whose job it is to access, transcode, and send data.
StreamToMe costs $2.99 on App Store and the server component is free.