Reputation System
I adapted this system from a Luke Gearing idea and have been using it for a few weeks. I'm pleased with it so far. It particularly suits a campaign featuring a lot of social interaction.
Take a blank table numbered 1 to 20—this is the reputation table. At the end of each adventure (or other significant milestone), have the players nominate a heroic event from the recent sessions. This event could be a successful boss fight, the discovery of a great treasure, or anything else that paints the characters in a positive light. Have the players roll a d20 and then write this event in the reputation table at the place indicated. If there is something already there, overwrite it.
Repeat this exercise for an infamous event from the recent sessions. This event could be a spectacular failure, something funny, or a ruthless act. Have the players roll a d20 and add the event to the reputation table, as above.
Now, whenever the party interacts with someone, roll a d20 and consult the reputation table. If an entry is there, the person has heard of the event, which influences their behavior. Don't worry too much about how the person learned that specific news — gossip travels more quickly than we realize. Also, it's possible that the information recorded in the reputation table is not strictly accurate, as gossip is often distorted.
Over time, you fill in more entries in the reputation table, meaning there is a greater chance that someone they encounter has heard of the party. You can use it for intelligent monsters as well.
I've been using this system for a few weeks, and it has worked well. Asking the players to nominate the heroic and infamous events is a fun little mini-game in itself. And having concrete information when someone recognizes the characters opens up roleplaying opportunities.
As an example, following is the reputation table for the characters in my Iskandar campaign:
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In combat, Jarrah the druid miscast a spell resulting in a rain of snails.
During All Fools Day, the god of tricks asked Whip the fiendspawn to "share a tale" with him. Whip agreed - and the god took his tail!
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The party broke up a bloodthirsty cult operating in the village of Vamech.
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The party fed a huge gang of Redcloak bandits to a zombie crocodile in an ancient temple.
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Jarrah the druid entangled a group of skeletons in an old cairn, and then Cammie and Whip absolutely destroyed them.
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Cammie the vila got really drunk after they raided a crypt and threw a drink at Captain Toriel of the March Guard.
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I commend this fun little system to you—please let me know if you try it out!