Edited to add:
While there's obviously some correlation between small n and the usefulness and reasonableness of the name, my point was not primarily related to length - the parenthetical was added as an afterthought. I was simply pointing out that the overwhelming majority of sequences of letters are not going to be easy to use or remember.
Prepending "get" (or sticking "app" on the end) always makes me kind of queasy, but it worked well enough for Dropbox. I kind of like Exec's approach of using iamexec.com.
I don't think such a system would be difficult to put in place on the web right now. Linking is done with whatever gobbledygook URLs you don't feel like reading, and if you want to revisit a page, you bookmark it with an alias of your choosing.
EDIT: I should say that I think this is the workflow for >90% of web users already. If they don't just use Google every time.
It's important to have a good name but not crucial and it doesn't have to be short.