Following is an uncomplete list of maybe alternatives for the raspberry pi (if it fits to your needs). The common intersection of all listed items is "usb, hdmi out, linux driven". It should be clear that the raspberry pi has a philosphy that differs from the rest :-).
Entries since 2012-06-27
Entries since 2014-03-04
These are populated boards from our first run of beta devices. They’re undergoing electrical testing alongside hardware and software testing at the moment, and if all goes well, the Raspberry Pi you’ll be buying in January (or by auction later this month if they all work as they should) will be exactly like one of these.Source
I am crossing fingers that beta test runs fine. It is so awesome that such a tiny device can do such a lot.
While browsing through the internet, i also found another device called CuBox. This device comes with a pre installed os, so it is really plug and play. The main advantage are the available ports, like hdmi, two usb, eSata etc. I found a german review on "Der Standard.at". I also stumbled over OpenELEC which is a optimized linux to run XBMC and has an easy to install (on hdd, flash etc.) guide. Maybe my i will plug in such a device in my tv at home soon :-D.