I see a lot of "Designated Yoga Spaces" in Yoga magazines and Design magazines and the one complaint that I've had - and the I've seen in reader-response letters (yes, I read those sometimes) is that they're all for people with loads of space - sometimes even an extra room or an extra house on their property.
Given that I have none of those things (we have 1190 sq. feet and you've seen our office) I thought I'd share my space with you. It would be really easy for you to duplicate. I've measured it and it requires floor space of 6 sq. feet - or an open yoga mat with space to extend your arms.
I double-mat because concrete is so unforgiving on the palms of your hands. Spend 5 deep breaths in downward dog and you'll understand. Sequences, pulled from issues of Yoga Journal, are mounted and taped on the inside of the office door, so that they're readily available when I need inspiration. They rotate out, except for the Sun-Salutes on the top left, which should be performed daily. To the left, off of the picture is our office and to the right is the open loft area, namely the couch. Directly in front is our reading (scotch/cigar) corner and the beginnings of Christmas shopping.
I have a view of both my monitor and my television, which is nice when I using a video because I don't have to adjust my space. I have a couple of DVDs, but I get the most motivation and variety from an online course at Yoga Today. They're free (and not paying me to gush) and so informative. The instructors can tell you where your focus should be, what your body placement should be, and what you can expect to feel from your muscles as you go through their sequences.
The space needs two things - a sense of serenity (which you can get either from meditation or the ambience of the room), and something to focus on when you're doing balance moves. I focus on the finial of the floor lamp by the card catalogue:
So ultimately, you don't need an entire room (or structure) you just need a clear patch of floor. And some uninterrupted time to find your breath. Namaste.