Wow, this thread is growing FAST! Let me add my two cents...
I like ScS's 'Stasis Gallery' idea, how about adding a little timer (Hour Glasses for each of the "paintings"), something that gets triggered when the characters enter the room, which shows when the stasis will end. Now, the players must find a way to get into the rooms behind the transparent walls in time, otherwise some BAD STUFF will happen - although not necessarily to the PCs, you know, the usual: some cute little baby happily playing within a circle of paralyzed wolves, puppies drowning and the like...
Your tavern-idea suggests that you are going for really weird, how about a small jump in time: in a room, the characters find one of the items they are carrying right now - an exact replica of it. Entering the area ABOVE this room will send the players back in time (through some unseen portals). Maybe just a few hours, maybe decades, in this case the item would have been corroded. Now you just have to make sure the player drops the item when in the past (because of illusionary floor, traps, or simply because some stones are missing). Maybe he sees the item aging rapidly as it falls down
Or maybe the illusion of some VERY bad memory the characters have? Slowly have the 'real' dungeon fade into some kind of deja vu. Have the PCs fought and lost against some particularly nasty creature? Recreate the scenario right before they met that creature, so they slowly realize something very bad is about to happen AGAIN, and they have no option but to continue in that direction. Or even a bit more obscure: put them back into school, their bodys turned into that of 12-year-olds, the walls of the Gears fading into the corridors of their school. Then they are intercepted by an old teacher of theirs, who leads them down the corridor, telling them all the time that the headmaster will rip their heads off for <insert crime here> again (forgetting their homework, talking in class, bullying their classmates,...)
I seriously hope you'll introduce us to your Gears-Artwork once it is finished!
![Wink ;-)](./images/smilies/icon_wink.gif)