Apache's MaxRequestsPerChild directive is not at all about limiting load; it says after serving N requests (or N connections in a keep-alive setting), the worker kills itself and another may be spawned in its place (subject to spare server/thread config). This mostly helps keep slow memory (or other resource) leaks in check by starting fresh every so often.
Did you mean to link to MaxClients[1]? MaxClients sets
the maximum number of simultaneous connections; any additional connections will be queued by the OS socket api (subject to listen backlog, etc).
I think waiting to accept sockets that you can't handle is a better solution than either accepting a socket to return an error message, or (much worse) accepting a socket that overloads your system. Unfortunately, sometimes it can be hard to set MaxClients to the right value that isn't so big that you get reduced througput, or too small that you don't use all your resources. (One thing that does help you get to the right number for MaxClients is to set MinSpareServers to the same value as MaxClients; you will avoid issues where MaxClients is too big and you start swapping during high load, but you don't notice it because things are fine with a small number of servers).
IIS [1] and other mature web servers like nginx [2] or apache [3] do this kind of thing for you and provide simple configuration on it.
[1] http://support.microsoft.com/kb/943891 [2] http://serverfault.com/questions/412323/nginx-503-error-in-h... [3] http://httpd.apache.org/docs/2.2/mod/mpm_common.html#maxrequ...