Heh. Don't I know it...ooo..mirror..um. Yeah.
My dad does this stuff for a living, being CPA and IRS certified and running his own tax prep business since 79. And, one of those blowoff classes in High School did some good: MOCE, or Mathematics of Consumer Economics, which covered smart shopping, figuring sales tax, counting back change, and preparing tax returns. I took another blow-off course like that in college, which dealt with mortgages, sinking-fund annuities, stocks, interest rates, savings accounts, and sundry real-life applications with formulas drawn from arithmetic through calculus and trigonometry.
And yeah, I love doing this stuff, just like I love cracking open computer cases and fiddling with the innards and building custom systems. Only downside is that it's a rather expensive hobby. As for tax returns, I've always filed at the earliest possible opportunity. Funnest year was 2000. Federal return, and 3 state returns since that was a rather adventurous year, living and working in 3 states which happened to have state income tax.