Mines gotta be back in '07 on the mainland, I had an entire mainland sim and had no object entry, no scripts, no rez and no push on. I started noticing I was getting pushed away from something (my avatar was getting repelled slowly away from a source) So i went to investigate and found some sort of portal at the source, well it was a spinning vortex with some kind of shader effect (this was before windlight) it sort of looked like a circle of transparent water but it was also shiny and spinning real fast. Someone else saw it and when they approached it they dissapeared... along with the vortex. I IM'd them and they were 'offline' or at least appeared that way, later on when they came back online I asked them what happened and they told me they were tp'd into this black void, even the sky was jet black (remember this was before windlight!), there was no water or land, just blackness and a wierd green prim that they were stood on, when they tried to move off of the prim to fall/fly into the void they crashed and when they logged back in they were back where the vortex was