One of the companies I work with is Geezeo. I wrote about them previously here. Geezeo recently launched the mobile application, a small subset of what they will ultimately deliver. You can sign up for the mobile beta on their web site.
What Geezeo Mobile provides is something very simple and very useful. Once you register your accounts on their site, you can use a simple SMS message to get your current balances. This is particularly useful for checking your credit card balances before you attempt to make a big purchase. Since Geezeo has some important partnerships in place, they can easily connect to your accounts at thousands of financial institutions. Setting it up is pretty straightforward, and using the SMS application is dead simple.
Give this a try, and give Geezeo your feedback. They also have a good blog on financial management.