How to access external data

Hello,

We have a Fuel app planned that we will have a need to read and write data to an external something. I've seen SQL data access statements so this could be a database if that's the only option. We'd like it to be a web service but I have not seen anything that says we could call web services. Does anyone know? Are there any other options for accessing external data? COM access or .Net assemblies? What things can we interface to?

Thanks for any help,
Kevin