I decided to enclose my monitor with a frame to look like a real fireplace mantle piece, and added in some slowly pulsating lights behind to mimic the soft glow of a burning fire. The entire frame and light assembly slips onto my monitor and can easily be removed after I've finished sipping my hot cocoa.
After having my desktop fireplace running for a few days, I can say that there's a psychological reaction to seeing the fire and feeling the ambiance the back lights give. I feel a warming sensation over my face and body as I type. The feeling is sublime.
Here's what I used to make mine:
Ready to make your own cozy fireplace out of your computer monitor? Let's go!