What if, every class had a generic "Summon" button, that could summon a creature depending on the person's "summoning" level. It would have to have say, a 3 min cool down rate. Like Crafting, it could be something that you had to work on for a long time in order to gain a level, and therefore would bring something new and challenging to PL.

The creatures could be used to battle, to hold items, and maybe even get into creature vs. creature fights.

On a side note, wouldn't it be interesting if you could revive in game monsters? Success would have to be a thing of chance (no chance!reviving red dot figures like OL!), but it would add a lot into the game.