Rampart Associates puts out a monthly newsletter called "ISP
Report."  It bills itself as "The Financial Newsletter for
Internet Service Providers."  You can get a free three month
subscription at: http://www.ispreport.com/

In its July issue, there is a list of the top 24 consumer
ISPs.

 1.  American Online                  19,600,000
 2.  AT&T WorldNet                     2,300,000
 3.  EarthLink Network                 1,335,000
 4.  MindSpring Enterprises            1,228,000
 5.  Microsoft Network                 1,200,000
 6.  Prodigy                             796,000
 7.  AtHome                              620,000
 8.  GTE                                 590,000
 9.  RCN Corp.                           522,000
10.  BellSouth                           500,000
11.  OneMain.com                         472,000
12.  Southwestern Bell                   460,000
13.  Road Runner                         320,000
14.  Cable & Wireless                    310,000
15.  US West                             275,000
16.  Juno Online                         270,000
17.  Verio                               260,000
18.  Voyager.net                         230,000
19.  FlashNet                            220,000
20.  Bell Atlantic                       200,000
21.  Internet Direct (Canada)            136,000
22.  Internet America                    100,000
23.  CyberGate                            86,000
24.  IDT                                  80,500