This is going to sound trite - but I use a notebook.
I have the things I'm working on, and a parking lot of things I think of/see/etc along the way.
Periodically - e.g. when I'm having a coffee, I go through the parking lot and (optionally) make them into tasks in the future.
If it's a webpage, I bookmark it and don't bother exploring - otherwise it's a recipe for going on some weird tangents. My bookmarks are a mess, but it's actually pretty easy to just search than come up with a filing system.
I have the things I'm working on, and a parking lot of things I think of/see/etc along the way.
Periodically - e.g. when I'm having a coffee, I go through the parking lot and (optionally) make them into tasks in the future.
If it's a webpage, I bookmark it and don't bother exploring - otherwise it's a recipe for going on some weird tangents. My bookmarks are a mess, but it's actually pretty easy to just search than come up with a filing system.