Some forums have the very nice feature of showing the results of a dice roll as an 'extension' of the post, rather than a whole new one. an example of what I'm talking about can be found at www.gaiaonline.com. This other method of display is more aesthetically appealing, easier to read and does not clutter a forum so much.

The second part to this would be even more useful: the ability to add modifiers to rolls (-1, x4, etc.). Due to the variable dice picture settings this may seem difficult, but simply creating a second, optional dice set that can be rolled along side the first could achieve this effect.
The other option is to offer two kinds of dice rollers. The first would be the already existing variable-picture one, the second would be numerical rather than pictorial (perhaps with variable font settings) but could calculate the result of the selected dice and modifier. For example, 2d8+6 would trigger an algorithm that randomly selects 2 numbers from 1-8, adds them together, adds 6 to that total, and then displays the resulting number (maybe with the calculations themselves displayed too). The ability to roll more than one set at a time would be a great bonus too.
The lack of variable ability has really put the battle system for my RP in a problem. I've devised a complex system that is severely limited by the current dice rolling options.

And here's one final bit of reason for fixing up the dice system: Your grammar is all off. "Dice" is the plural form of the word, where you have it listed as singular. The correct singular form is "die". You also have the plural listed as "dices". While this is technically correct, it is more unusual than "dice".
Singular: "die"
Plural: "dice" (or "dices")

This little issue is my biggest problem with Forumotion boards. I hope this is remedied soon because I don't want to have to move, but my RP has certain needs to really work. Thanks.