Steven Sande from TUAW.com put together a list of things he would like Siri to be able to do. Because Siri is still in beta, there might be a chance that some of the features will be added to the final version of Siri. Hopefully Apple will also release an API for developers, so they can implement functionality to Siri.
His list includes things like the ability to check into FourSquare, Tweet without sending a text message, make a reservation at OpenTable restaurants or buy things through amazon.com.
Head over to TUAW for the full list.