Here's a game that I played almost ten years ago, and then ran into again recently: Frenzy.
In Frenzy, there are three different rounds, and in each round three different Battlefields. The goal of the game is to score the most points by winning Battlefields. Frenzy is real-time, which means that you don't have to wait for your turn. There are seven total piles of cards on each side of the table - one under each Battlefield (this is your Front Line - you and your opponent compare these to see who wins that Battlefield), and one under each of your Front Line cards (these are your Supply Line, and the top card of each pile goes to whoever wins the Front Line). Finally, each player has a Headquarters where he can only place Heroes. Each round ends when one player has placed three Heroes in his Headquarters, or when one player has run out of cards. At that point, each player scores the top Supply Line card for each Battlefield he has won. Repeat two more times and whoever has the most points wins.
The best thing that I see about Frenzy are the Heroes. They usurp the normal order of power in the game. Each player has Warriors with strength from 1-4 and some Heroes in their deck. If there were no Heroes, then almost every game would end in a tie with both players playing a strength 4 Warrior at the front of their Battlefield. Fortunately, there is an Assassin (Hero) that defeats strength 4 Warriors but loses to every other unit. Without these Heroes, this game would not function.
In addition, Frenzy came with four different "Factions" that could be purchased. These included the Undead, Orcs, Humans, and Dwarves. Each of these have the same basic deck, but include a different additional Hero (such as the Lich for the Undead). This adds slightly more variety to the game, but each of these Factions had to be bought separately, and it they did not really add enough extra variety to justify the extra $10 or so that it cost to purchase them.
Now for the biggest con with Frenzy - the game is too trivial. Unfortunately, even with the Heroes, I don't think that Frenzy managed to strike that elusive balance between having enough things to concentrate on to make the game challenging while having little enough that players can play it quickly. Striking that balance is the crux of a good real time game. Specifically, I think that Frenzy does not have enough that a player must pay attention to. Basically, if you only pay attention to the front lines and ensure that you are winning them, you will wind up winning the game. Yes, there are cards that could actually cost you points by winning a Battlefield (specifically, if you wind up scoring a Wizard, they remove themselves and one of your other Score cards from your Score pile), but it doesn't hurt enough to force you to actually watch for them. Whereas Jab: Real-Time Boxing forces players to pay attention to everything that is going on to prevent themselves from losing in whatever way they are neglecting (knockout versus judge decision), Frenzy only has the one path to victory, and thus becomes too simple.
Overall, I give Frenzy a 5.5/10. It is honestly better than I remember it being the first time I played it, but it is still not good enough to warrant me recommending that you try it out, unless you really just love real-time games.
If you like little card games, then you might also want to check out Lunch Money, Poo: The Card Game, and Skallywaggs.