I think the crystal ball in the player owned house is seriously overlooked for many accounts, including OSRS accounts. The crystal ball can be used to change one elemental staff into another, for example, a normal earth staff into a normal air staff. This does not sound like a big deal, and for a normal account it is not, but getting access to elemental staves in various regions of the game can be quite difficult since some regions require them to be gathered from clue scrolls. With just a single elemental staff, the player gains access to unlimited elemental runes, but is restricted to just one type of rune at a time. This can take a lot of the hassle out of enchanting or alchemy. The higher tier crystal balls can change between battle staves and mystic staves as well, but they are more difficult to access, requiring gold leaf, which can only be bought at a few locations in game. That being said, I think this is some of the most useful lesser known content in the game, that which is perfect for restricted accounts.
