Did You ever wonder, how many ways there are to tie a tie?
Thomas Fink and Yong Mao (two physicists) wanted to know it exactly and used a formal mathematic/physical approach: 85 ways to tie a tie. But only 13 of them are considered aesthetic. The book also contains some background info regarding the history of ties.
Links to the book:
By the way: in 2006 the typical German man spent 23 Euros per year for ties (source).
Another statistic say, that 21% buy at least one tie per year.
Video tutorial for Full Windsor Knot at VideoJug.