So along one particularly long train of thought involving a browser-based dungeon crawler, I had the notion of inventing some kind of RPG combat where every encounter is resolved in a single round. No more mindlessly mashing on attack! This is, of course, predicated on the notion that you're in some kind of dungeon-crawling-balanced game where the point is to conserve resources.
Each encounter is nothing more than a power level and a list of attributes. These attributes include your standard elemental considerations and monster types, but they go far beyond that in various ways. Most importantly, when you're dealing with groups of monsters, it's still the encounter that has the attributes, only now they've got attributes like "heterogeneous" or "band." There's also a table of how much damage the encounter will deal, but I'll get to that later.
Every ability a character learns, apart from an optional MP cost (or whatever), is just a table of positive and negative modifiers against the various encounter types. The flavor should reflect why it's powerful against some enemies and weak against others. So each character in the party picks one of their abilities, and the relevant bonuses and penalties for that ability based on the encounter type are added to that character's level.
You compare the resultant number for each character against the encounter level, and you sort each one into one of five categories of effectiveness representing how near the two levels are and in which direction: ineffective, poor, ordinary, good, and great. Or something like that. Based on the number of characters who fall into each category, the encounter deals damage to the party, whose target(s) and amount are described in the table for that encounter.
If an enemy's level is so far below your own that using the basic attack for every character will automatically put the party in the highest entry in the effectiveness table, where typically no damage is dealt, the encounter can be skipped.
This, of course, makes it easy to make lots of different encounters... or, if you don't want to do that, it also makes it easy to let the player come up with a macro for every single encounter, further streamlining the process.