My phone has a memo app, it's usually used for ideas for coursework, possible programming ideas and drunk thoughts. Some of them make sense later one, some don't. If I have a tricky bit of (CS) coursework I prefer to mull over it away from the computer. If I understand what the coursework requires and vaguely how the system works then it's not always necessary to always consult documentation - the gaps can be filled in when it comes to implementation. For example, I can think about some code that requires the computer to convert a string to an array of bytes but I don't need to know the name of the Java method that lets you do that, only that it's possible. Walking, taking showers, doing the washing up and preparing dinner are all great activities for thinking. It's just a shame that when I'm not doing any of those things my mind is probably occupied (mostly uselessly) reading or watching stuff on the Internet...