I assembled my own sous-vide apparatus with pieces I already had lying around my kitchen and a dented crock pot my sister was about to throw away. I really love the versatility and convenience. I can vacuum seal a steak in the morning, pop it in the water bath when I get home from school, and take it out and sear it whenever I feel like eating. Once the commercial versions come down in price a bit (they hover around $450 now) and the general public gets wind of it, it's sure to change home cooking. I won't get into the particulars of sous-vide cooking, others have covered it much better. There are tons of resources on building your own and cooking with it.
So far I've only cooked one rib eye steak and a couple pieces of chicken, but I was pretty impressed. The steak was closer to medium than I intended (was aiming for medium-rare), but after fine tuning with my precision thermometer I think I got the temperatures dialed in a little better. I'm looking forward to experimenting with this little contraption. If I continue to get good results I may have to invest in a vacuum sealer. Right now I'm just using Ziploc bags and a straw to make the vacuum.