To be convenient, I collect most widgets on my website, if they are publicly available. You can find 7 of them here: http://www.completechesscourse.com/puzzles.html
I am not endorse any of them. The problems can be easy, difficult, or anywhere in between. I just make it easier to find them.
As I said in my other posts, doing one problem a day is not training, instead it is entertaining. But entertaining is also beneficial.