I've noticed there aren't a lot of con-artist crimes around, so here it goes:
Crime name: Glimmer-dropper
Crime Description: Go convince someone to buy a 25 dollar ring for lots and lots of money using the glimmer-dropper trick. One of your friends should dress up like someone with money and walk up to a well-populated shop or bar and ask if anyone has found his very expensive ring he lost nearby. He should make something up about huge added emotional value or legal consequences to add to the price, so it sounds plausible when he offers a huge reward for the finder. He then hands out his phonenumber and leaves. An hour or so later you should come in with a very shiny, but very cheap ring which looks like the one the rich man described. Claim to have you found it outside, and if all goes well, someone in the establishment is bound to offer you a bucket of money for this worthless ring. They hope to make a profit when collecting the reward, which is ofcourse non-existant.
Snitch Info: You need a friend or mobster to pull this off, preferably with bluffing. He should look as wealthy as possible so good transportation and an impressive outfit should help. You'll either have to invest 25$ for the ring, or you could use some treasure item.
Crime Success: It could go wrong if they give you the finders fee phonenumber like honest people, but who's ever seen an honest man in Master City? It's quite safe since your victem might not even know he's been conned, and would be hessitant to call the police if they did. The amount of money you can get depends on the reward you can offer plausibly (depends on your friends bluffing and outfit), and how good you can haggle while selling the ring.