My collectiong goals have changed over time, as a lot of ours tend to do, but the one thing I have stuck with, and continue to work on, is my quest to complete every Allen & Ginter set. I know not everyone loves A&G, but to me, this pays the perfect tribute to the early days of card collecting, while effectively translating it to the modern size.
One of the toughest years for me to find cards, though, is the inaugural release of 2006. While they have had to evolve their design as each year's release comes, 2006 gave an almost identical replica of the original issue. The pictures are basic, and there is little else, but the player name and company logo.
I got a significant addition to my stack in a trade with Night Owl. In return for a few cards from 2012 Topps and a Dodgers relic card, I got quite a few 2006 Allen & Ginters. I still have a long way to go, but this is definitely a great help.