That's a hard question...
I honestly can't tell how I discovered LPL nor when I visited the site for the first time. But it guess it was at sometime in 2007...
But I can tell why I wanted (and still want) to be a part of this site.
Well I started collecting live recordings at the LPP (a pretty big former LP fansite) back in 2007 I think (not sure). Many recordings back in the days had no exact informations when or where the show took place. I tired to figure it out and this Live Guide was the best help I could get.
Then in 2008 I attended my first LP show in Frankfurt. After that I wanted to know everything about their live shows and LPL was and still is simply the best source for that.
I was kinda fascinated how you got all this informations about nearly every show even from some 2000 shows.
Over the years it became more than a live guide and today it's one of the biggest LP communities out there.