How to put a file in RAM (Was : Re: Clear the computer's memory?)

[Loïc Martin]

Not trying to hijack this tread ;) but the things I learnt (swapoff/on 
is a welcome trick, thanks a lot) but reading it leads me to a question 
: is there an easy way (dont mind the command line, but best if drag'n 
drop is enough) to copy a (movie) file entirely in ram, then read from 
it (the way you did on AmigaOS with the ramdrive)? Any ramdrive enable 
by default, or any way to easily create one and mount it?
I've got 1G  ram since I had to do heavy graphic creation, so I've got 
enough unused ram atm. It would spare the hd, be less demanding on pw 
(laptop), and moreover might solve the annoying glitches you have when 
playing a video with lots of program accessing the hd in the background 
(amarok, moving files, installing apps and especially update-manager 
that runs quite a lot in a development branch ;) )