Oscar's Grind
The first reference I can find regarding this more modern betting system appeared in Allan Wilson's "The Casino Gambler's Guide," copyright 1965. Wilson was intrigued with this system after a dice player named "Oscar" produced detailed records showing modest, but consistent profits. Wilson ran 280,000 sequence simulations on an IBM 790 mainframe computer that was available to him. The analysis showed that while Oscar was a bit on the luckier side, his claims were at least possible. Now remember that Oscar was a pass line bettor only attempting to buck a -1.414% house edge as compared to a -5.263% house edge for double zero roulette. In addition, Oscar had a mega-bankroll and the willingness to risk it all for a one unit per cycle win.
Let's look at the details of the "Grind." The system has the player bet one unit. If he wins, the sequence is over and a new one can be initiated. If the wager is lost, then the next bet will be the same size as the one just lost. Whenever a bet is won, the next stake is one unit larger, unless it causes the bettor to net more than one unit of profit for the sequence. At that point, just enough is wagered to net one unit if the bet wins. That's it! A sample sequence might look like this:

1) Bet 1 unit and lose: -1 unit
2) Bet 1 unit and win: +0 units
3) Bet 1 unit and lose: -1 unit
4) Bet 1 unit and lose: -2 units
5) Bet 1 unit and lose: -3 units
6) Bet 1 unit and win: -2 units
7) Bet 2 units and win: +0 units
8) Bet 1 unit and lose: -1 unit
9) Bet 1 unit and win: +0 units
10) Bet 1 unit and win: +1 unit -Series has been won-
The player starts with a loss so his second stake remains at one unit. This bet is won, putting him back to even. Because he is only seeking a one-unit win for the progression, he does not escalate his bet to two units. Bets 3 through 5 are losses so he stays with a one-unit stake. After the sixth bet wins, he now increases his wager to two units. The seventh bet also wins, but again he only needs a one unit bet to win the sequence. The eighth bet loses so the ninth wager is one unit. Finally, the tenth bet wins and the player wins the entire progression. 
Notice that out of ten total wagers, nine were only one unit in size. This system tends to be more conservative and less volatile. The sequence illustrated above contained five wins and five losses. I like the fact that this system does not quickly escalate your losing wagers and blindside you like some of the others. However, as your losses outnumber your wins, the amount you must wager after a win will steadily mount. 
Oscar's Grind will excel in streaky games. The Grind minimizes your betting level if you are amidst a string of losses. It also directs you to gradually increase your wagers during a streak of wins, helping to optimize profits. This can be one of the safer systems to use if you limit your maximum bet size or impose a stop-loss parameter for choppy games. If you plan to use Oscar's Grind, I would recommend a stop-loss of about ten, no more than 12 units per cycle.