[paulgb]

Two things I would love to see:

1. Kayak.com for ground transportation. Trains, buses, ferries, etc. are a pain to compare prices and book right now. Admittedly there probably isn't as much of a business case for this.

2. A music site where I could collaborate on a playlist with my friends and listen to the music at the same time. Currently there are sites that let you share playlists, but not listen at the same time as other people.

[abi]

I wrote a solution for #2, that's exactly like what you guys want! Check it out. http://youconcert.appspot.com

The version that's up there was written in a single Caltrain ride but I have a lot more features after coding some more. I'll push those changes in a couple of days but let me know what you guys think, would love to hear any feedback.

[jasoncartwright]

In Europe Kayak does some ground transportation where it makes sense to compare it with air travel - on the Eurostar http://www.eurostar.com

[TrevorBurnham]

There's a startup called Catapulter.com that's pitching themselves as Kayak for ground transportation. They're in closed beta right now, but opening soon.

[duke_sam]

#2 is partially handled by rdio (http://www.rdio.com/) you can create and share playlists and any number of people can listen to them. Not sure about collaborating on playlists but considering the heavy social aspect of the site I would be surprised if that feature never arrived.

[JED3]

This is true, but Rdio still lacks the synchronized playback to the followers of a list, unlike what we're used to while listening to a real 'Rdio'. I believe this is what makes paulgb's idea proposal unique and all the more attractive to me that something out there would allow me to "listen to the music at the same time" while collaborating on what gets played next.

Examples: http://hackermusic.com, http://tunez.sourceforge.net/

[alexophile]

Yeah, when you create a playlist on Rdio, you can choose collaboration options: anyone can edit; only followers can edit; nobody can edit. And, as far as I know, there's no limit to the number of concurrent listeners.

[mpc]

re #2...where do you see the music being sourced from? Allowing listens on shared music via user uploads would be a legal nightmare and the major APIs only provide 30 second clips.

[paulgb]

That's admittedly one big and non-technical problem with that idea. A lot of songs are available on YouTube, so one way is to have people find them on YouTube and paste the URL to add a song to the playlist. You could use the player API to synchronize the audio between listeners.

I would go the user-upload route myself though. Just make it non-trivial for users to rip the songs to their hard drives. By the time you get a C&D (if you do), you may have enough traction to start talking to some of the labels about licensing content.

[petervandijck]

Don't do a music startup, even the best ones continue to fail against the legal barriers. It's a graveyard of cool products buried by legal, why go there?

[JED3]

What about a service that acted as a relay for a remote user streaming their own collection of music?