Usually this just involves a tab or another category but honestly I haven't found many systems that implement leads and opportunities in a unique manner.
Preferably I'd like to move away from business but it can't be helped. Anything that often moves into personal lives become someday/maybe lists or pending/reminder/contact style systems that assumes a clear route and a clear timeline.
There's some like GTD's context concept that asks you to make a list specifically for your next action when you're in front of someone and there are habit trackers/weight trackers/nutrition diaries that remind you specifically of an item to take or a timeline of your logs but everything I've come up since to go back to the missions and visions type of route if not the business route of this one whole wish-list.
It would be kind of cool to have a productivity concept centered on say... seeing a poor person/remembering their face/clothes/etc/planning in the future on how to scout that person's problem and needs - inserting it into a note regardless if you don't meet that person for years and then needing only that snippet to create a roadmap set of action targetted at that person.
Of course this can be used for malicious needs like marketing purposes but still... google analytics for the real life brain seems like it could train us people to be more altruistic without more instantaneous or temporary in our help. (i.e. merely dropping a quarter on their empty cans) It also seems like a step productivity systems haven't explored yet.