One of my characters was a shaman of a tribal jaguar-god, which was trying to contact her and warn her about an impending battle. Due to the distance between the two, he was unable to contact her as well as he'd hoped, and as a result his messages came in the form of half-remembered dreams.
The dreams themselves were generally a couple of paragraphs in length, varying between around 10pt and 16pt size. The more important words were generally larger. Once I was done writing the dream I would read it myself to judge how long it would take, and would use this as a guideline on how long the player got. Then, during the session I would wait until the character fell asleep and hand the player the note, telling them they had however long to read it (in both cases I used it, I gave them 10 seconds).
The overall reception to the mechanism was great. The player panicked slightly whenever they got a note, as they were aware of the time constraint, and in the morning they had a suitably hazy recollection to give the rest of the party. It had a very organic feel - rather than assume that the character would only remember so much and tell the player, "This is what you remember," I gave the player all the information and let them simulate the haziness of the dream. It also let me around one of my great hatreds - telling the player something so that their character can just repeat it verbatim to the rest of he party.
Obviously, the system will have its flaws. I've used it twice and don't plan to use it again in the near future, as I think that it could become blasé if repeated over and over. If the player is a slow reader, their character may not gain as much information as you'd like. Also, while hurridly reading the note will result in patchy information, the player tended to pick up more about the start of the dream than the end (which makes sense). I'm not sure about how to solve this problem unless I make an intoductory paragraph which lays out the general structure of the dream (a device that seems somewhat awkward IMO).
Any opinions? What are other tricks or gimmicks like this that you've used?