Forum Moderators: phranque
The best solution seems to be the Apache module mod_limitipconn.c (not available at all web hosts). I found some examples of using mod_limitipconn at http://www.webhostgear.com/279.html
Using mod_limitipconn I can set a limit on the number of connections per IP address. This is exactly what's needed and I won't have to ban any download clients.