You could have a spell system which essentially has a technical spell language with it's own grammar. Brave but foolish individuals could just try out new spells and see what happens. Or more serious casters could figure out the rules for themselves and make new spells on demand.
I like this idea but how would you combat such a system being put on the web once solved and thus reducing the timesink/mini-game aspect? Not so much about the stopping of webposts but rather varying in-game mechanics that make such actions negligible. Off the top of my head I see something along the lines of each person's affinity with magic being a unique relationship and thus applying a different subset of rules for learning magic. For example a strong fire affinity might mean adding more water elements in a water-based spell to offset the players extra fire affinity (dumbed down version). Do you have an alternative?