Shiny. The Firefly 'verse is detailed and meaningful. The characters have realistic motivations, and the show achieves humor without breaking the fourth wall. Most episodes are very deep and artistic; it's no stretch to say that one must watch a few of them four or more times to fully grasp their subtleties. I especially recommend "Out of Gas", but you should watch "Serenity" (the episode, not the movie) first. Do not watch Serenity (the movie, not the episode) until you have seen all the episodes.
Honestly, this is an incredible series. You should watch the whole thing; if you're paying attention to the details, it's definitely worth your time.
Games (and other electronic entertainment)
Words cannot express just how much this game puts all others to shame. This is the only game I would truly call "art". The story and visuals are subtle and detailed and the characters act like they have genuine personalities. This game takes extreme risks in storytelling and contains the second most effective cinematic sequence I have ever seen, movies notwithstanding. (The first is the Firefly episode "Out of Gas".) I can never view games as a genre the same way again.
Play this game. It's easy to acquire a copy—I found one on eBay for $15. I'd gladly have paid ten times that. No joke.
The Myst series is fantastic. The original game was groundbreaking in the industry; one of the first games to place any value in the aesthetics of the world. The original Myst was the first game that encouraged the player to explore the world for exploration's sake, because it was the first game whose surroundings were beautiful and detailed enough to make the player feel like they were there. My favorite of the series is Riven; it has the best feel, although the puzzles are too difficult. However, as the series continues, it declines. I recommend not playing Myst V at all. On the other hand, I highly recommend the novels set in the Myst universe, especially Myst: The Book of Ti'ana. The story is well-thought-out, deep, and serious.
This is a life-changing book. It's also an incredibly difficult read; I had to re-read sentences, paragraphs, even chapters to understand them at times. It was totally worth it; GEB will change your perspective on math, music, art, patterns, logic, human nature, consciousness, and even morality. Hofstadter is a genius; to give just a brief example of the sort of brilliant writing this book contains, one chapter is written as a dialogue about musical fugues. However, the chapter itself is written in the form of a fugue. Each discussion of an aspect of a musical fugue is itself an example of a literary translation of that same aspect. There's also a chapter that reads almost the same backwards as forwards.
Reading GEB will not be easy (unless you're a genius yourself), but it's completely worth it—make it a life goal to get through it someday; you'll never think the same way about anything again.
Other Various Things
Yes, a comic strip. Calvin & Hobbes was noteworthy for its portrayal of serious philosophical, religious, and political ideas through the adventures of a boy and his stuffed tiger—but don't think it's blatantly didactic; it's still hilarious. It used space in an unusually artistic way for a Sunday comic, and (I think) took itself more seriously than comics had before.
If you're not convinced, check out 25 Great Calvin and Hobbes Strips, which has some lovely commentary.