A-B Repeat and extending playlist options

Hi guys
I'm planning on working at making some extra options for playlists and bring a-b repeat style option for playing media back.
I'd love to get it so, like with the DVD bookmarks, you can jump to a point in a media file and play it for X seconds. So you could mark sections of music or dvd and then have a playlist of them all.

I'm still putting together a design spec on what i want to get working so if anyones got any ideas let me know.

One idea i have is tap into the existing events to fire a next track option after X seconds when you play your playlist. Think this will need no real back end changes and just needs a editor function to create the events. (i'm thinking a web-based one for now, moving to adding orbiter screens later on)

Again i'm still just throwing ideas around at the moment.