my guidelines to .biz
1. It must be relate to Business and fit the .biz TLD. If you can't say someone they are in the _______ (fill in here with domain) BUSINESS, then it probably doesn't fit.
2. If all or most other TLD's are not taken, it probably isn't worth registering.
3. Don't register "brandable" names in .biz, stick with generic names. Those wanting a brand will make something up or buy it in .com.
4. Register domains that would have lots of potential companies that may want it. I only pick .biz if there would be hundreds of companies that would want the generic, not just a few. (JetEngineRepair.biz would be harder to sell than laundromat.biz)
5. Large market companies won't normally use a .biz. Pick names that appeal to companies that won't care who has the .com.
6. With character domains, only LLL.biz or NNN.biz have foreseeable value. LNN, NLN, etc generally won't.
7. You won't get much traffic with .biz. The value of them is being generic, short, and either potential for development or development itself. The more generic the better. (i.e. Gold.biz can be use for gold records, gold mining, gold bullion, or gold medals. - GoldJewelry.biz is still good, but more limited, goldpencilholders.biz is probably too specialized even though generic)
8. Pick names that could have multiple uses in multiple markets or multiple levels in a vertical market. For example, jobplacement.biz could be used by a large international company for hiring, a large career search firm, a small employment agency, or an independent recruiter. It could also be used for Biz to Biz, Biz to Consumer, or possibly Consumers to discuss businesses. The more potential users the better.