How about this for a super-short version of Toms foreshadowing thing.
Every time you roll encounter dice, roll two. Every roll *something* happens, or you find something, but only 1 in 6 is a full-on encounter.
(the DM remembers/improvises what each thing will be.)
1. Skeletons. 1. Sub-sensory ('aware' feeling.* )
2. Orcs 2. Tracks/Sign
3. Wolves 3. Spoor/remains/Victims
4. Bandits 4. Sound/noise
5. Rival Team 5. Brief/distant sight
6. Vampire 6. Encounter (They see you and respond)
So I roll 2,5. "Right at the end of the corridor you briefly see a shadow pass before the light. It looks like an Orc."
(Of course 4 or 5 could turn into an encounter if the players are fuckwits, but that's up to them.)
If they are being loud then you could say that the largest result rolled will always be in the right column, making a physical encounter more likely, but the monster maybe less threatening. if they are being stealthy, you could do it the other way round. Probably just an indication but the thing itself may be horrible.
So now the players are in a continuously 'alive' environment that they have to keep thinking about all the time. You keep the improv quality so the foreshadowing is not separated in time from the encounter, its not 'inevitable' or pre-set. (I know it wasn't in Tom's thing anyway.)
Its random for the fun and regular enough to represent a real space and environment. Its also a good return on result for minimal arrangement of data.
And they are always finding things out, just by being there, like a real place.
It might not work in the same way as Tom's foreshadowing as the phenomena don't always match in the same elegant way.
(*like horror movie music, somethings wroooong wOOooOOoo)