We can't always be on the computer- real life has a way of dragging you away, after all. That's why this forum is here- to talk all about it.
I maybe remember them for like 10-15mins after I wake up, but haven't really had some that I've remembered past that. Sometimes I can wake up and forget exactly what I was dreaming about (talk about bad short term memory lol).
It partially has to do with what part of the sleep cycle you're in more than your memory, or so I've heard.
Yeah that's why dream books usually recommend writing your dream down first thing.