one of the greatest pulp games i played, was run by Rich, the creater of .45 adventure, and the encounters simply lead you around, finding clues, chasing things down. "pass a brains test to translate what a local is saying, when you pass, you find out about something happening at the moseleum. there is no encounter cards at teh moseleum, but once you get there, u automaticly trigger another event, in this case, i found my lost co-worker, dying of a wound, who shared another piece of cryptic advice, him dying just before the big plot spoiled. then i headed to the new hinted at location. and low and behold, i found the item i was looking for, after searching the area piece by peice ( it was inside a lion shaped fountain, and the clue was something like 'in the belly of the beast'
so your encounters could simply be story line events, traps, helpful items, and clues as to where they should search for special 'set in place' events.
i think everyone has put some great ideas together on this !