ORIGINAL: nickj
Slipping is about losing altitude without gaining speed, not losing speed, but it's a good technique if you have a short approach (i.e. big trees on final). Alternating slips seems to be asking for trouble, though.
I was talking mainly about doing it on a trainer (and really only when I am goofing around).
But I think with low wing loading aircraft you can generally put them down in super tight areas without the use of slipping, flaperons, flaps, etc. Its just a matter of practice.