Magic loop is a technique that has become quite popular of late. You can use a long needle to make any item in the round -- I use it for knitting sweaters, two socks at once, two sleeves at once, hats, mittens, center start shawls...
I learned the technique about ten or so years ago, for doing socks. I later discovered a vintage pattern from my mother's collection for a doily, starting in the center and knit in the round on a long circular... I'd already been doing that with center start shawls! So, the method isn't new, but the interest in using it has been renewed!
Anyway - as for a "short circular that gradually gets larger as you need it to" - they are called "interchangeable needle sets" and they are made by Denise, Addi, Boye, Knitpicks, among many more...