Michael Ross touched upon using MLM's to "find" top-selling products. I second Michael's terrific point-- that is a great place to cultivate products to sell.

MLM oriented products offer some terrific advantages:
1. The usually have some sort of exclusivity about them-- so a person can not usually find them in a retail store.
2. They usually have a "fat" profit margin, which means if you "knocked them off" you would be able to under-cut the MLM and still provide a terrific profit margin for yourself.
3. MLM's put a lot of time into creating sales literature for their products, which gives you a head start in creating sales literature for your own product based on the MLM's product.
4. A top-selling MLM product usually has some recognition within the market so you can use that to help sell your "knock-off" product.

Here is a brief plan on how to use MLM's to start your own business and help you create your own products:
1. Research MLM's with product lines that interest you.
2. Find out what their top selling product is.
3. Join the MLM.
4. Build a website specifically around that product.
5. Gain some sales and experience selling that product-- forget about recruiting. Focus on starting your businesses, fine tuning your infrastructure and building a customer list.
6. Research how to "knock-off" the MLM's top-selling product.
7. Start selling your own product.