What I'd like to see is more "kick-inna-nuts"-sites, meaning that site has some evil, if not fiendish, surprise. These could include:
- sites (found or not) that cause % chance of assassination attempt by some thing (void-thingys?) in the province
- sites that when found, cause a horde of some evil monsters to attack and reclaim the province. If searcher is killed, then province becomes neutral and site becomes hidden!
- sites (found or not) that give afflictions other than disease. Some misleading message might be included, such as "Some unknown assassin tried to kill your commander, but he got away with a wound."
- summoning bonus sites with a chance of "backfiring" as in R'lyeh's Void Gate
- different (all fatal) diseases, such as decreasing strenght, attack, leadership
And then

umroll: spells to provide these effects, too!
- Humer