I have a nice to-do list app on my phone called Clear. One of my saved lists is a bunch of whiskies I'm interested in buying. I check off the ones off I've tried or bought already.
I user Clear for simple to-do lists, shopping lists, etc. It's brilliant in it's beauty and simplicity.
I use My Life Organized for serious nested project management. A little clunky and not as beautiful but it is very scalable and robust.
There is an app called Check. It was designed more for to-do's, but you could easily name lists after those you want to give gifts to and make unique lists per recipient
I use Trello all the time. It might be a little much, but it's the same concept : make a list named after the recipient and add gift ideas. This one would let you connect and share links to (maybe helping you find the best deals?)
You could try Clear, https://teuxdeux.com or also eventually Trello. If certain tasks take longer and you want to give them a certain time frame you could simply put them into google calendar.
https://itunes.apple.com/us/app/clear-tasks-reminders-to-do/id493136154?mt=8 for ios.
https://play.google.com/store/apps/details?id=com.xuchdeid.clear&hl=en is a copy of that app for android, haven't found anything better.
Clear is great because it's completely gesture-based. Pull down to add a task, swipe it to remove it.
With other apps, pressing tiny buttons is work enough for me not to use it.
I use Clear to capture ideas on each of my devices and keep them in sync. Initially an idea is only an item in a Todo List: Ideas. When I have more thoughts about that idea, I create a dedicated list which can handle multiple thoughts around that idea. Only in one Todo App it's possible to elaborate an idea to a concept.
Once that isn't sufficient anymore I use Trello and a dedicated GitHub repo to organize each project.
Clear. It's a fantastic To-Do app for the Apple ecosystem which would be absolutely perfect as a Universal Windows 10 app. I love how well designed it is. Looks very Metro.
Clear – Tasks, Reminders & To-Do Lists
Clear is the revolutionary to-do and reminders app that makes you more productive. It’s as easy to use as pen and paper, and once you start organising your life with Clear you’ll wonder how you ever managed without it.