Gentlemen, do you know all the ways to tie a tie -- and which knots are best for which outfits and occasions? If not, don't fret; the How to Tie a Tie app is here to save the day. The free version (available on Blackberry, Droid, iPhone and iPad) offers pictorial and written instructions to guide you through 12 different knots. The paid version offers 20 different necktie knots, plus two bowtie guides. Even those among you who can pull off a four-in-hand in your sleep might want to consider widening your repertoire of knots. It gives your whole look a subtle kick, taking you from fine to fabulous. And with the app right on your phone, you can take your knot-tying tutorial anywhere.