Send pings to many computers in the local network in parallel, on the command line with the free Swiss File Knife for Windows, Mac OS X and Linux.

Display either a list of replying devices or a graphical permanent info. Requires administrator rights, as the API calls used for ping don't work in a normal user context. Source code is available for self compile.
sfk ping ip [ip2] [to ip3] [options]

check if machine(s) on given ip(s) reply to pings.

default with only a few target adresses is
to show a graphical display of replies.
with many addresses a list of replies is shown.

experimental command. may not always list all
available machines, especially on embedded linux.

may require admin rights with Windows 7.
if you get an error, right click on cmd.exe
and select "run as admin" to enable sfk ping.

graphical reply output
         .         no   reply
   0 ... 9         fast reply, 0 - 9 msec
   A ... Z         slow reply, >= 10 msec

   to n            ping range up to n within the same
                   class c network (up to 100 addresses)
   net n [n2]      ping 192.168.n.1 to 192.168.n.254 if
                   computer runs in 192.168 network
   net r1.r2 n     ping r1.r2.n.1 to r1.r2.n.254
   mynet           ping the network of this computer

   -time           with single ip: show reply time
   -every ns       with graphical ping only:
                   ping every n seconds (default is 1s).
                   use 10s when pinging internet servers
                   over longer time, to reduce server load.
   -maxwait n      wait up to n msec for a reply
   -maxwait ns     wait up to n seconds
   -list           send just one ping and show result
                   as a flat list without graph
   -stop           stop on first reply from any ip
   -range s e      with "net": ping from s to e
                   instead of 1 to 254
   -pure           print just replying ip's
   -quiet          print less infos
   -quiet=2        show no OK etc. with -stop
   -noterm         output is not for terminal but file.
                   writes only one ping summary per minute.

web reference

see also
   sfk pingdiff  find new devices in the network
   sfk tcping    check if a server accepts connections

   sfk ping -stop -maxwait 600s
    +sleep 1000 +then run "" -yes
      waits for a ping reply on given ip,
      then runs after another delay.
   sfk ping
      ping these two ip's in parallel
   sfk ping 130 140 2.150
      ping IP .130 and .140 within current subnet
      and .150 in the .2 subnet
   sfk ping net 1 2 10
      ping whole subnets 1, 2 and 10, like  to  to to
      if your computer is within 192.168.x.x
   sfk ping net 192.178 3 5
      ping to 254 and .5.1 to 254
   sfk ping mynet
      if my computer has an IP
      then this pings to .254