Or turn off your computer completely to have 100% free RAM. This advice is not as helpful as it seems if your line of work is, let's say, a JavaScript or Flash developer or you want to use anything more advanced than a blog.
That does not address lots of use cases. It also introduces an inconvenience that is pretty much a no-go for regular Joe's out there. The problem is that an average user is now forced to buy a new computer every 3 years because Flash and JavaScript take up too much RAM. Sure an above average user might go through the inconvenience of setting up two browsers and learning what JavaScript and Flash are, but your standard spherical bear will not.
As for developers, matters are worse. For one, I have the pleasure of working with (debugging, deploying, writing) JS and Flash code. I would love to use the extra 2 GBs of RAM for running 3 more virtual machines to do more testing, but I cannot.
The solution is not to bury our heads in the sand, but to fix the memory leaks and/or memory requirements. As the OP points out, there is no reason that a web page that can be encapsulated in a half a meg of HTML needs to take up hundreds of megs of RAM once parsed and running.
