Perhaps I'm excessive, but I have pretty much every email my partner has ever sent me. I hold on to everything. I don't have any particular way of highlighting the lovey-dovey ones, but they're there if I want to find and read them. Since hard drives only get larger and larger, I figure I'll keep them indefinitely.

I also save some of the sweet texts he has sent me over the years. I lock them so I don't accidentally delete them. When I'm going through deleting other old texts, I see those and they make me smile. I don't know what I'll do when I get a new cell phone -- probably throw them to the wind and wait for new ones to arrive. :)