Historically I'm not a guy who likes "fancy" note-taking or TODO-tracking tools. I tend to prefer things like vi or TextMate. That said, I played with WorkFlowy last night and I really liked it. I think it provides a very useful kind of tool experience. Scratchs a useful itch. I was surprised. The only thing that I don't like is I'm uncomfortable with it being a webapp hosted by some company. I'd much much much prefer it if I could run a native app version of WorkFlowy, with my data stored in a file on my own computer. And if it's stored in a file(s) that I control, then I could, say, use something like DropBox or git or rsynch or TimeMachine or TrueCrypt or whatever to make sure that data is shared or backed up or encrypted exactly how I want or need. Right now if the WF company goes away or I have no connectivity, I can't access my data. (I'm aware of their "copy-and-paste out" feature but that doesn't address this particular problem, and is hacky and will be prone to having out-of-date data stored in your backup cache. And it's too manual.) This is my only negative with it so far. Otherwise, I think the UI is great and I think it's really useful for certain cases. Possibly a killer app for those use cases. Turn this into a native app for Mac with all my data stored locally wherever I wish, with no connectivity requirements, and you can put me down for a purchase. Great work!
I also want to throw a shout out to Notational Velocity. First time I've heard of it was in this discussion thread. Just played with it now. Also like it. Nice use cases supported. I can see this really being useful. It's a different beast than WorkFlowy so I don't think they compete, they are complementary or orthogonal tools, at best. I could see using both. Couple advantages I see with NV are (1) native app, (2) open source, and (3) it stores your data locally where you control it and own it. NV does not have the cool collapsible hierarchical bullet point UI mechanism that WorkFlowy has, however, so again they don't really compete directly or scratch the same itch. The 100%-keyboard-drivability aspect is awesome and very useful. I wish I could control the font size, the default is uncomfortably small.
Anyway, glad I discovered this thread, and I'll be adding both of these tools to my toolbox going forward. Kudos to the folks behind both.