I never used Notational Velocity, but this seems like an awesome UI to use for Notes. As long as you have powerful search you can always find your notes by their content and create new ones when the ones you find aren't relevant.
How many times I've created a new note related to something I wrote about before, but didn't want to search for. Now I'd basically be forced to search for it when I tried to create the new note and I'd assume this would help keep all those thoughts and ideas at least somewhat related to each other.
It really is great, I've been using it for years -- and all my notes are stored as plain-text (markdown) files. Only downside is images really. If you want to try it, check out this more-recently-updated fork. The creator of the fork is apparently working on a replacement that I'm rather looking forward to trying.
nvNotes[1] was great, but the latest version removed Dropbox syncing (because the developer was using an older API that is being deprecated) and now it's... no so useful. Combined with nvALT[2] on the Mac, this used to be a great combo.
How many times I've created a new note related to something I wrote about before, but didn't want to search for. Now I'd basically be forced to search for it when I tried to create the new note and I'd assume this would help keep all those thoughts and ideas at least somewhat related to each other.