
My next choice is an all inclusive media center case made out of Lego blocks. Here's the process I'm using.
Step 1: Add some heat sinks

I know, I know this isn't necessary but I'm hyper paranoid. I live down in Texas and let my house get fairly warm while I'm at work, plus I converted my fireplace to be my media center. Those things are known for reflecting heat, not dissipating it, so I'm putting on a heat sink will also be adding a little fan once I decide how tall my case will be. (I changed the way the heat sinks were placed right after this so that they are in line with the HDMI which is where I plan on putting the fan)
Side note: I used the thermal tape (SKU: PRT-09771) from sparkfun Link
This heat sink (FISCHER ELEKTRONIK - ICK SMD E 15 SA) from Element 14 for the LAN9512 chip: Link
And this heat sink (FISCHER ELEKTRONIK - ICK BGA 10 X 10 X 10) from Element 14 for the SOC: Link
Step 2: Get the measurements
I don't want a case where all the ports are exposed, I want my cables concealed within the pi for the most part so I need to take some measurements on the size of the pi + how far the cable sticks out before I can start manipulating the cable. So with everything plugged in, I traced around it and then measured the dimensions

For those interested, the HDMI is on the right, SD card on the bottom, and so forth and so on. If I wanted to keep everything inside I'd need to make the case 7 1/2 inches wide and 7 inches deep. That's a little too big, so I'm planning on orienting it with the HDMI to the back and SD card/PSU to the right. The SD card will stick out along with the power and HDMI cable. This will let me unplug it easily when it freezes and swap out SD cards. It also means the space the pi takes up is a much more reasonable 4 inches deep and 5 1/2 wide