The only thing missing in my photography kit, was a decent zoom lens to make wildlife photos and maybe shoot some close-up photos of artists at festivals. At first I was thinking of getting an 18-200mm lens, which would then replace the 18-55mm kit lens that came with my camera. After reading some reviews, and giving it some thought I dismissed that idea, because all the reviews mentioned that the image quality wasn't all-that, and well... I've gotten fond of the 18-55mm kit lens; it's extremely light, and it performs pretty good.
While browsing the web I noticed that the Canon EF 70-300mm f4-5.6 IS USM was on sale at a store in Barendrecht. I decided to read some reviews, and generally liked what I read and saw. Today, Xariana and myself were in the area anyway, and I decided to make a little detour and pick one up.
It's big, it's heavy and it makes my camera look badass; I love it 
Oh and more importantly, it makes some very, very nice pictures too! My kit is more-or-less complete now; Maybe I will get a nice macro lens someday, but that's more a long-term idea.