Theyre called recumbents and can be either bikes or trikes. I owneda trike for several years and it was the best thing Ive ever ridden for most purposes. Faster than a roadbike especially downhill and on the flat (but slower uphill) and far far more comfortable - no bum pain, never fall off, head up position lets you admire the scenery. They take a while to get used to pedalling - you can't stand up so have to really pull back as well as push down, and you really learn to spin esp on the hills. Great for touring, can carry a heap of gear, and actually felt safer in traffic than an upright - drivers really notice you and go way around! And an absolute hoot down a long twisty mountain road eg Buffalo or Falls Creek..
Melbourne is one of the recumbent capitals of the world with at least 3 major manufacturers all of whom make excellent 'bents (look up MR, Trisled and Greenspeed)
Go and try one!
(I eventually sold mine cos it wouldnt fit in the car!)