I'm pretty sure I read somewhere damage type is going to be a mod slot on each power and the powers animation would be defined by what damage was slotted. So I was thinking about possible customization to damage type, and what I came up with is introducing dual damage type mods. So for example, instead of just doing fire damage, maybe you slot a fire/crushing mod. Now my idea is that there would be a primary damage type, which defined the animation, and a secondary damage, which would mean a fire/crushing mod would have different animation than a crushing/fire. Also the total damage for a dual mod would be the same as the damage for a single mod. Now to make it more interesting you could have the vendors just sell single damage type and have dual damage types crafted, rare drops, or maybe bought from the Star Store. You could even make a couple of different dual types. You could have one that was 75% primary and 25% secondary damage and maybe a 51%/49%. That way you could have crafting or the Star Store one type of dual and rare drops another, and since the total damage would always be the same, it wouldn't unbalance the game it would just make it easier to defeat certain opponents, notably the once that were resistant to your primary damage type.
Now to make things truly interesting, I would propose a new damage mod call something like chaos. This mod would randomly change its damage type and thus animation. Ideally this would happen every time the power was used, but if that was to resource intensive you could instead have the first chaos mod you slot buff the player. This buff would be something like a 5 minute auto-renewing buff, and every time the buff renewed it would randomly select a new damage type. Under this model, all of the chaos mods a player had slotted would do the same damage type. There is also a compromise between the two previous models, which would be having each chaos mod buff the character so that each chaos power's damage type would be independent of each other.
You could refine the chaos mod even more by having multiple types of chaos mods which did different types of damage. For example, you could have an energy chaos that randomly did fire, ice, electrical, or energy damage and then a physical chaos mod that did lethal or crushing. You could also have a grand chaos mod that randomly did every type.
Anyways, that was my random thoughts for the morning.