Be careful about how "original" the party company is...in other words, you want your guests to do business with a reputable company that backs their products up!
If you're looking for more practical...yet reputable parties, there's Tupperware and Watkins Products (spices, etc for cooking and baking...great stuff!). You'd have to check either a website or your phone book to see if they host parties in your area.
I think there's some kind of toy party, too....at least there used to be (see what I mean? maybe it wasn't that reputable). People may need to replace things, order more and add on or at least have it guaranteed.
Avon is another good example of a great party to host...always guarantees their products for any reason.