hmm interesting stuff, i'm not sure my experience can be diagnosed as sleep paralysis, as I was able to move and speak.
It was in November 05, and I was in my uni halls at the time, I had been out that night but I had only one or two beers, but I was still back at my flat pretty late about 3 in the morning. Anyway I went to bed, but woke up an hour later with what seemed like someone pushing on my head (my quilt was over my head at the time, so I didn't see anything), it quickly disappeared though, so I ignored it as my imagination and tried going back to sleep, but this time I felt it again except it was like someone was pressing and pushing down on my chest and head, it felt quite heavy, like a body.
I freaked out at that point, jumped out of bed and grabbed my hurl (Irish sport's stick/bat), and started swingin it about in the dark...must have looked quite funny, but I switched on the light and there was nobody there.
A few days later I was putting a poster up on my my wall beside my bed, and I noticed for the first time, there were two faint black handprints just above my bed, in the area just above where I felt someone pressing against me. The prints were quite well formed, the fingers looked very slender so I assumed they were the handprint's of a girl. I certainly never saw them on the wall before even though I already had put posters up beside where they were.
I had one other experience in that room similar to the last, but that was a few months later, but I do believe there was something very odd about my room.