The points above are a few of the obvious ones. The others are more subtle but very important. At Focused Web we don't try to beat the search engines using some clever trick or quirk to gain an undeserved advantage for a short while. The the search engines and directories want to supply the best and most accurate information to their visitors possible. The better they do this the more visitors will return again and again.
More visitors directly equates to more revenue from advertisers.
We work closely with the technical staff at each company to stay abreast of the latest criteria for robot evaluation. The major search engines and directories have historically not charged for a listing. This situation is changing. We view this change as positive. With this special program it can take as months to get listed in Yahoo.