Is there a certain item type that I need to create in order to add miscellaneous items to any POs? We often purchase a variety of things from vendors just once, so we don't want to create a permanent item for them. Instead, we just want to be able to add a miscellaneous item to a PO so that what we are ordering and what we are paying for matches up.

It all depends on what you planning to do with the item, and will it be lot numbered/serial numbered or not, do you want to keep the inventory or not.

I was able to create a other charge for resale, and that worked. Thanks @Suitestallion

No problem, make sure you check the box for Can fulfill/Receive and generate accrual, if you need.