[dela3499]

For freeform stuff (usually website mockups), I'll usually just grab a piece of paper or use Inkscape.

Inkscape is probably a decent tool for thinking (at least if you're already familiar with it), since you can zoom in and out on an infinite canvas, draw and type things, etc.

[senko]

Shameless plug: try https://awwapp.com/, it's a free-form whiteboard (as in drawing) webapp that lets you do exactly that (+ real-time sharing).

[dela3499]

Thanks for sharing. Perhaps it's better to make the free version have more (all?) the features, and then charge for having more than one drawing. It's a bit hard to commit to paying for a service before I've been able to use it successfully. A pro account is required to move items around, for instance, which makes it difficult to see what it would be like to use the full version of the tool.