I think, perhaps, that collecting happy memories is the best thing that you can collect. As you get older you can always look back on the better times, or times that have shaped your life, or changed it for the better. But sometimes you can forget the good stuff, and somtimes we don't have any happy memories, Thats all really sad.. but thats not what this is about.
If you died, and assuming you had an afterlife, wouldn't be wonderful to have your memory collection with you? 'Cause in your after life you can't take anything with you. But you can have as many memories as you can hold.You never see ghosts flying off with color TV's do ya?
Anyway, in your afterlife you have all of your memories. I think that a good memento of your time on earth would be music. Even in life music is good because you can sing your favorite song to yourself whenever you want, even if you are dirt poor you can sing a song that reminds you of the better times....
Another good memory would be stories. If you had a crappy life you could always look back on books you've read or stories you've heard. They could keep your mind entertained for a while...
I can't think of anything else to say, and I'd better stop before I get too irrelevant....