I too use Varmit Al's Bi-Fur Pods. I made two sets. Walnut for me and a shorter set of oak for the kids. I killed elk & antelope off them last year.
I also have a Caldwell bi-pod. Shortest model available. Works good & sturdy enough. No springs in the height adjustment, just telescoping twist lock sleeves. I seldom carry them afield.
Another option is the Snipe Pod.
http://www.snipepod.com/ They're pretty cool, weighing about 6oz. I don't find them good for shooting strings as I have to reset the feet after each shot and you can't use them as an unattented rifle rack like you can the Bi-Fur pod, Harris or similar models. I have a "sitting" length and in a pinch have used the upper sections as a prone bi-pod. I killed a whitetail off them last year too. I usually have these on my belt, even if I'm carrying my Bi-Fur pod.
A friend of mine is the inventor, engineer, chief marketing rep, etc. You can catch him at the SHOT show, FNAWS, Safari club Intl. shows too. Cabela's was carrying them but I haven't checked lately. I don't know if you can order them direct from him. I picked mine up at the shop.