engine - 6:58 pm on Feb 4, 2001 (gmt 0)

Very interesting.

Yahoo is by far the top. Here's a top five example of a site well listed:
Yahoo 49.21%
Excite 17.27%
Google 12.91%
MSN Search 8.55%
Lycos 6.45%

Here's another site not well listed in Yahoo directory but well positioned in all engines.
Altavista 65.94%
Excite 10.86%
Google 7.97%
Yahoo 6.52%
MSN Search 3.62%

And one more not well listed in Yahoo directory.
Altavista 29.64%
Google 22.14%
Yahoo 18.21%
Excite 14.64%
Lycos 7.5%

Although the traffic is satisfactory on all sites, I believe the boost in a Yahoo listing would send the traffic up further. Although, not necessarily through the roof.
I believe volume of traffic is irrelevant. Some sites achieve 100k+ hits and others are 100+ hits.

In addition, despite it's good listing in Yahoo, one of the sites has as little as 30% coming from all search capabilities. All the other traffic comes from links on other websites/bookmarks and other methods to achieve site vistors.

I'd still support the notion that a Yahoo listing is a valuable asset.