
SSDs, I believe, have now overtaken memory as the single most cost-effective upgrade
Sticking one in a laptop that's maybe 3 or 4 years old and already has 4GB of RAM just gives it a completely new lease of life. And now you can pick up a 64GB jobby for about £40 ... it really can make an old laptop usable again for general day to day stuff.
And of course in new PCs it's on a whole different level...