On episode 70 of the App Stories podcast, John Voorhees and Federico Viticci discuss apps for managing big projects, including Keep It and one of my favorites, DEVONthink. Federico also points out a really nice trick for saving web pages as webarchive files on iOS, using Workflow (soon to be Shortcuts).
All you need is a workflow that accepts URLs as input. Pass the URL through a Get Contents of Web Page action and then use the Get File of Type action and, in the file type field, use
com.apple.webarchive. It worked great in my initial tests and I think it will come in handy in the near future as I have some research to do. You can get the workflow here. Although Shortcuts should be coming this fall, you can still grab Workflow for free on the App Store, and the consensus seems to be that Workflow workflows will transfer over to Shortcuts shortcuts, so you should be set.