The downside to "don't wait to do the things that matter" is what to do when you empty that bucket list early. I've covered the geeky bucket list stuff. (making video games, blogging, open source contribution, IT jobs, BS in CS, ect.) I've covered the more stereotypical bucket list stuff too. (Skydiving, performing onstage, time with friends, writing the novel, marrying the right girl, ect.)
At this point in my life, there's nothing new that interests me that hasn't already been done. It's made life pretty boring at this juncture. I've lived out all my dreams and now it's all just like "Okay, now what?"