Free-to-play games are the obvious example. MMORPGs are another, though I would say they are somewhat less sinister as — while they use many psychological tricks to keep players coming back — they are at the core generally an attempt to produce an interesting or enjoyable game world, which is generally not the primary goal in F2P games.
I feel one of the worst (or at least most interesting) offenders for gambling is Valve, through Team Fortress 2 and Counter Strike. In those games people can buy "keys" to open randomly dropped "chests" which may or may not contain valuable items (valuable in the sense that they can be traded to other players for sometimes hundreds of dollars in Steambux). They are essentially running a lottery. I will concede that it's quite similar to Magic: The Gathering's business model (small chance to find something valuable!), but something about the exact implementation (perhaps the ease of trading and valuation of items, or the heavy use of Steambux which can only be redeemed in a Valve store?) Valve uses feels a bit more skeevy.