I love doing my taxes.
Regardless of whether I am entitled to a refund or have to fork over some of my hard-earned money, I take great pleasure in the process of filling out my tax return. I like all the calculations, the challenge of having to understand the word-problem-esque nature of some of the line items, the satisfaction of having everything nice and tidy and accounted for at the end of the day.
I realize I am in the minority on this one, for sure.
Doing my taxes falls into the same highly satisfying category as other (generally-hated) tasks such as filling out forms (census, doctor's office, school applications), maintaining a detailed spreadsheet of my business revenues and expenses, and balancing my checkbook (back in the day before internet banking when I actually still bothered to do that).
I also love jigsaw puzzles - the really hard kind, with a monochrome pattern and 1,000 tiny pieces. In my crazy head, all of these things are members of the same family.