for someone who doesn’t particularly want a blog, and wants to jot
things down and save them with as few clicks and as little distraction
as possible.

The entry interface: go to the app’s URL, get a text entry field. No
login, no nothing. Hit the Save button and your note is in fact saved
(maybe at the button-hitting stage, you could ask for a login and
password, if the app is configured to use that option). maybe there’s
an optional title/keywords field.

The retrieval interface: another URL, perhaps accessible from the
first. Start typing in a search field, and notes that match what
you’ve typed start appearing below it. (ala Google Suggest, of course.
this may or may not be easy to do with full text search, or it may
create a ceiling on how many notes the system can deal with.) You can
optionally set a login on search, or perhaps just on seeing the whole
entry. This page should have robust javascript navigation, ideally you
shouldn’t have to touch the mouse to go all the way through to an entry.

The whole idea is to center the UI on writing, instead of on reading.