To-Do List Widget is a widget app that allows you to create a to-do lists and show it on your home screen.  You can pick how much space a given list takes up on your homescreen; obviously the more space, the more of your items on your list can be displayed at once.  You add items to the list and you can check them off when you are done.  An incredibly small widget taking up less than 300KB after installation.  

Docs To Go is an all-in-one editor for Microsoft Office files, and also contains a PDF reader.  Whereas other such apps may take 50+MB or bigger, this app is only about a 5MB download and is less than 20MB once installed.  It can read, create and edit .doc(x) Word files, .xls(x) Excel spreadsheets, .ppt(x) Powerpoint presentations for Microsoft Office 97-2016.  It can also read PDF files.  Expect ads for the free version, though.  There is a premium version for about $17.  

Granted, 20MB may not be considered small for a standalone app, but given that this is effectively multiple things rolled into one app, it still belongs here.