actually, I rather thought of this as something kept on a commlink, possibly an implanted commlink. To be found when you kill another runner, or a fixer, or a corporate middle-to-high-ranking guy.
interestingly, you can also plant on an enemy runner's commlink intel about the present run (that this dead runner's team gathered, supposing that both the players' team and the NPC runners team have the same goal).
Better yet, if you need to bring your next plot differently that just "your fixer contacts you, he has a Johnson interested in hiring you because you are good fighters", you can plant info on such a commlink, that will be at the center of the next run. For example, when your hacker sifts through the dead guy's commlink, he can discover, "hidden" among a lot of junk (it's important that there should be a lot of junk, see below), such things as:
- previously stolen paydata (hehe): weapon schematics, internal memos from research teams about a new kind of drones (I like the idea of half-drones half-living machines research, or androids like those in Philip K Dick's "Blade Runner")
you should have it related to a previous run your team made, or to something you want them to do in the future, so that the runners can actually try, through their fixer or other contacts, to find someone interested in the stuff
- intel about the present run (things the PCs have not found, and things they did): useful to help them see that crucial piece they missed, when you thought it would be the first thing they checked
- contacts, especially fixers or 'useful' guys (cops, barmen, anyone you could extort intel from, depending on what level campaign you play: street, corporate, etc)
if those contacts are friends, it should be possible to find chat or email logs about what they do (the BDSM fan, the humanis pointy-hatter, the corrupt cop)
- the place and time they should meet their own Johnson, in the case of enemy NPC runners.
for useless junk:
- passwords or sentences that look like they are passphrases, if possible combined with a list of favorites bars (adresses, a summary of what drinks they serve): it's funny to see the runners go in those bars and tell the barman "power overwhelming" or "there is no cow level", which of course he won't understand, and think the runner is loco…
- favorite shops or restaurants
- Urban Brawl stats
- keys to empty bank coffers or private storage
- an of course, agents and black IC