In addition to just plain wanting to see it, I wanted to see Frost/Nixon because it was nominated for best picture Oscar. Using this list of best picture Oscar-nominated films, I've seen every one since 2000 except for The Pianist and generally about half of them since the 60's and one a year before that. My movie list watching began in 1998 when the AFI released their original top 100 films list. I've seen all those and am now working on their updated 10-year anniversary list (which unfortunately means I might have to finally watch Titanic.) I still need to see 8 of the 23 additions to the original list.
I'm also working on this list of the top 50 cult films from Entertainment Weekly. I've seen 15 so far, some are among my favorites (Harold and Maude), some are bizarre documentaries about Karen Carpenter shot only with Barbie dolls, others are about Jackie O's crazy cat-lady relatives that screech show-tunes and feed raccoons whole loaves of wonder bread.
Other lists I keep track of are best books. The Modern Library released a list of top books after AFI did the movie thing. The reader's list, conducted by Internet voting, was unfortunately swamped by objectivists and scientologists, but the lists by the board of the organization are actually interesting. I think the non-fiction list is especially humbling; I've read a whopping two of them. I think my best is the Radcliffe version of the novels list, where I've read 32 or 33.