Ask HN: What is a useful, minimal app that doesn't exist yet?

To quote an old book: "That which has been is that which will be, And that which has been done is that which will be done.

So there is nothing new under the sun."

More than likely, there is no app that hasn't been done. There are only ones we don't know about.

An idea on the front page of ideaswatch.com looks pretty easy and useful -- bill splitting for roommates.

It has of course, already been done. It's too obvious to have slipped through the cracks. But if you want to build something small that'll help lots of people who need help -- that would be a good one to tackle.

There are plenty of other good ideas at http://www.ideaswatch.com

In general: another interesting spot to look for ideas are features of bigger applications, that either are badly implemented, to hard to reach, ... and make optimized standalones. E.g. even though Photoshop can crop images, there still is a market for tools that can do that and be done before Photoshop has finished loading.

2 random ideas:

Probably exists, but I don't know about it yet: Something that automatically or as-easy-as-possible deals with timezones (possibly as a browser plugin), showing me the time in my local zone. I can copy-paste to Wolfram Alpha, but that isn't perfectly smooth.

A YouTube frontend that can filter subscriptions, even better if it can split series automatically. E.g. many channels have multiple running series, posting them alternating, I'd love to see them as separate channels/ignore ones I'm not interested in. Identify common title prefixes/numbering schemes, break them out into separate displays. Solves the issue that not all channels provide playlists, and I can't subscribe to only playlists or "evrything except those 3 playlists".