The number of Web Service APIs for data storage in the cloud keeps growing. The latest entry comes from startup Nirvanix and you can see our Nirvanix API profile here. Nirvanix describes their storage services as an Internet Media File System (IMFS). It's a fairly rich API with nearly 75 pages of Documentation. Their API comes with reference applications (always a good idea for API providers) in PHP, Perl, Java, C# and interestingly Adobe AIR.
If you check our list of APIs tagged "storage" you can see there's at least seven available at the moment. Your choices include:
With offerings from Microsoft and Google due any time now, this will be become an even more heated market.