The AT3IONT-I Deluxe is small by design and necessity. In its principal role as an entertainment system (Home Theatre PC), the thought is to keep things small so that your enclosure choices can fit into a typical home.
Looking at the top down view, we can see the familiar lines of the Mini-ITX layout. The most dominant feature is the large heatsink that serves the dual purpose of cooling the Atom 330 CPU and the MCP7A (ION) chipset.
Looking at the image below, we find that the Atom 330 is another CPU like the older Pentium D. There are two physical CPU dies on the packaging. This style of Atom has been replaced by more traditional multi-core designs. In fact, the Atom 330 is listed as End of Life by Intel. That should not be a deterrent, though; there are plenty in the channel to replace one if needed.
Along the upper edge of this massive piece of blue anodised aluminium we find three fan headers. ASUS has also left a 9-pin serial port on the board for some reason. Also visible in this shot is the WiFi Antenna port and power port for the included power supply.
At the bottoms of the heatsink we find the four SATA II ports, the Wireless N mini-PCIe card and a single PCIe x16 slot (in case the built-in 9400M IGP is not enough for you).
Along the right edge of the AT3IONT-I we find two slots for RAM. These support up to 1066MHz DDR3.You can see where the original ATX power connector was supposed to be. Above this along the same side we find a single 4-pin Molex connector. This is for peripheral attachments. Included with the system was a single cable that plugs in here and allows you to attach three SATA devices. This is a little odd as there are four SATA ports on the board. Looks like you are going to lose out on at least one of them. There is also no option for any Molex or 4-Pin Floppy power connectors. This will remove the ability to use many multi-card readers.
On the I/O side of things, we have some good options for such a small board. You get a Wireless N antenna port, a VGA port, a HDMI port, 4 USB 2.0 ports and some great options for audio. You have TOSLINK optical, 1/8-inch stereo plugs and even dual RCA plugs (stereo only). Oh, and that little blue thing is the Bluetooth antenna for the board (yes, it comes with Bluetooth, too).