The rest have all been posted now - soz for the delay, I've been poorly (caught it off the kids, as damon will testify!) Mmm... the locked groove - without attempting to sound like I'm some kind of genius, it was me that suggested it - I bought a Godflesh LP in about 1988 and it does it at the end of that album. I just thought it was amazing, so I suggested we rip it off - they end the album on some bone crunching feedback looped forever.
There was something else really cool I wanted to try that I found on a Kate Bush record - concentric grooves. Two grooves run 'parallel' on the vinyl and it's basically pot luck to which song you get depending on where you put the needle down - with the Kate Bush record, it didn't tell you this, so I bought it (it was a 12", maybe 'running up that hill' or something) and I played the a-side about 5 or 6 times and then when I put the needle on the record to play it again I suddenly found myself listening to a different song! It freaked me out, so I took the needle off the record and put it down again and it played the wrong song again. I was convinced I must have turned it over and maybe the stickers were the same, so I did it again and this time it played the main track again! Like you, I asked the guy who ran the record shop I bought it from about it and he said he'd had stacks of people bring copies back. It was him that told me it was a trick called 'concentric grooves'. I've also seen records that play from the middle out and Sonic Boom did a record that was designed to be played at either 33 or 45 for different effect and it worked pretty well. we loved all that stuff - coloured vinyl, clever sleeves, nice tactile stuff - the promos for sublingual with the tear open strip were one of my favourites. Clear CDs was another first. All the kind of stuff you can only try when your label has wonga!