My SO got 4 thermoses for Christmas one year, so I decided to build a simple wishlist service[0] to prevent it happening again. Launched it 6 years ago, and since then it's been used by friends, family and myself for all Christmas and birthdays - so I consider it a huge success. In addition to already being a success for me personally, it's growing organically, and last year really picked up the pace when I reached 1k users. Now it's at just over 7k, which is surreal.