Which kind of Inventory to you prefer?

I would love to have a poll. Give me some additional programmers, and everything will be possible

You can probably find some decent existing ones floating around on the web mate. Nothing wrong with using other peoples modules.

I'm pretty sure Calli would be able to whip one up with a bit of php & mySQL. Something to consider for the future I guess.

It really depends. As mentioned before: If inventory puzzles are a main "feature" of your game its mostly good to have an popup inventory which are also visually some kind of bag or pocket the character actually has.