Ok... one of the biggest challenges that Shadowrun GM's seem to come across is creating a Nuyen Karma balance when awarding PC's. We typically see topics on it every couple of weeks here. Award too much Nuyen and Street Sams get the short stick, too much cash and you'll see PC's blowing money on high lifestyles because unless you are a rigger or a street sam you've got nothing worthwhile to spend your cash on...
Not only that but big run payouts really limits who you can offer jobs from. If the PC's won't get out of bed for less than 20K each, then who the heck can afford to hire them? You're pretty much stuck with offering jobs from Corps and Organized Crime syndicates. Unless you totally handwave the funds that other people might have available there is zero grey area for the PC's to get hired by a squatter community being menaced by gangs, or a down on his luck reporter who needs paydata for a big scoop, or anything like that... Why would the PC's even do a run as a favor for a friend if it meant they were getting paid peanuts? Hand-waving it gets pretty ridiculous too. I remember the old adventure Dark Angel where the PC's were offered one million nuyen by DA's girlfriend... Seriously, the guy hadn't even released an album yet... How the heck was the girlfriend of a supposedly struggling rock start supposed to scrape that kind of money together?
Now I've mentioned on here several times in the past that the Nuyen Karma ratio that I've found works well is approximately 5000 nuyen for every karma. This means that by the time a mage has accumulated 20ish karma for an initiation, the Street Sam has about 100K to upgrade his ware with. For a long time I sort of left the ratio at this and was happy with it... it worked... sort of, but I ran into the second problem of there being too much cash floating around. I wanted my PC's to scrimp and save... worry about how they are going to make rent on next months low lifestyle, remind them that they are the underclass, subhuman trash, dreaming of the big score that could set them free and let them live the high life on some nice tropical island somewhere... It just didn't jive with the fact that after 4 or 5 runs their bank accounts would be sitting and 80,000+.
At any rate, now that you've heard me bitching I'd like to toss out my idea for a solution. I call it the shadowbank (because hey it's Shadowrun we can add Shadow to anything and it sounds cool). Basically the shadowbank exists as a purely metagame mechanic. The characters have no knowledge of it, and the players only have a rough idea of its balance. I track it for each PC behind the screen. Now for each 1000 nuyen that the PC earns they only get to see approximately 100 nuyen of it. The remainder goes in the shadowbank. After the shadowbank has reached a considerable balance, the player can request big ticket items from it, and I will find a way to give them the opportunity to get their hands on the item for free/cheap. Want a move by wire system? Well maybe that Yakuza Oyuban you just risked your life to save is grateful enough, that he is willing to fly you to Chiba all expenses paid and get you wired up in one of the best black-market cyber-clinics on the planet... Want a slick new ride? Hey that Mafia hitman you just assassinated had a Westwind parked out back, and the keys are in his pocket. Sure you'll need to scrub it for RFID tags and the like but that's a small price to pay. It also makes the cool toys that the PC's get their hands on have some narrative weight. That weapon foci is no longer just some piece of gear your physad picked out of the book. He took it from the cold dead hands of the the Yakuza ninja that he killed highlander style in a duel on a warehouse roof...
This also keeps the runners poor... If a run that would have used to have have paid them 20K now pays them 2000 suddenly financial management becomes a bigger issue. Burning through clips of EX explosive ammo or flinging grenades left and right will start having a significant impact on their bottom line. It lets you keep the game at a 'street' level without causing major issues balance wise.
By fiddling with the ratio you can even still reward players financially for jobs that might pay very little, or nothing at all. Maybe they would be willing to help out the squatters being attacked by ghouls in exchange for a hot meal and a place they can use as a bolthole in the future if they know that their shadowbank balance will still go up. Maybe the won't be quite so irate when the Yak Oyuban tells them "Do this gratis or I put a price on your head!" if they know they are still going to get something out of the deal.
You can even fiddle with it further and customize the ratio to each character. Spellslingers in Shadowrun are often perceived within the game world as being more 'valuable' than other archtypes. It comes up in the fluff all the time. Mages are also less likely to need to draw on the Shadowbank so it is entirely possible to up the mages cash to shadowbank ratio to 200/1000 to represent the fact that they command a higher price than a street sam.