ping for NT:
-t Ping continuously until interrupted - usually by Control-C or Control-Break
-a Resolve addresses to hostnames - that is, if the Internet name service (DNS)
   has an inverse (address to name) entry for the IP address, give you its name.
-n count - How many pings do you want to send?  The default is 4, but, for instance
   when I'm mapping a subnet, I usually use 2.  One to "wake up" the system in 
   question, and one to make sure I get an answer.  Multiple pings are usually done
   for the purpose of getting a measurement of the latency between two hosts (or 
   host and site), as well as its variability.
-l Send buffer size - The default NT ping packet is sent with 32 bytes of data.
   If you believe that a larger (or smaller) packet size will noticeably affect
   the response time from the target host, then you may wish to experiment with
   different values.  The range of sizes is from 1 to 65500.  Note that values 
   (for Ethernet) require that the packet be fragmented for any value over 1386
   bytes in the data field.
-f Don't fragment - Any IP packet whose size exceeds the MTU (Maximum Transmission
   Unit- effectively the largest packet size permitted for the connection in
   question) for the local and (possibly, I'm not sure) intervening networks needs
   to be broken up into pieces to make the trip.  If the send buffer size (above)
   is larger than the MTU and the -f (Don't Fragment) flag is set, then ping cannot
   deliver the packet, and the user will be notified.
-i TTL Time To Live - Every IP (Internet Protocol) packet has a TTL or Time-To-Live
   set inside the packet.  Its purpose is to prevent endless routing loops, so every
   time a packet goes through a router, the TTL is decremented (or reduced) by one.
   When (or If) the TTL reaches zero, the packet is discarded and an ICMP TTL
   Exceeded message is returned to the sender.  This mechanism is taken advantage
   of by tracert (TraceRoute in NT spelling)to track each router through which a
   packet travels.  If the TTL is set too low, the packet may never reach its
   destination.  Also see the note at the end about reading the results of PING.
-v TOS (Type of Service) - I don't know what this one means.
-r Record Route - for r number of hops (1-9) - I don't know what this one means.
-s Timestamp for # hops - I don't know what this one means
-j host-list Loose Source-Route - I don't know what this one means, but source
   routing is generally discouraged on the Internet.
-k host-list Strict Source-Route - ditto
-w timeout - This is supposed to limit the amount of time in milliseconds that PING
   will wait for an answer from the target host.  In my experience it's worthless.

NT RESULTS
Time returned is limited to a lower value of <10 ms.  This is because the system
clock used by the command interface is governed by the 64K ticks (approx 18.2 ticks)
per second.  Unix systems generally run a faster clock tick, and so can handle a 
finer granularity in time returns.

The TTL (Time-To-Live) returned can be used as a clue to the Operating System (OS)
of the target system.  Network equipment and Unix servers generally return a TTL
of 255 (minus the intervening number of router hops).  NT machines return 128, Windows 95 and 98 generally 128 except Windows 95 OSR 2 which returns 32.  HP 
networked printers usually return 60, and a little research will show more details.


Unix - NOTE: These answers are based on RedHat Linux 6.1, but are generally consistent with other flavors of Unix.

-s packetsize - Number of data bytes sent in each packet (like -l above).  This
   can range from 1 to 65507.  In Linux, the number of bytes returned is 8+s.
-c count - How many packets to send.
-f flood - Send packets as fast as you can.  Generally reserved only for root.
   This can be harmful to some servers and serves no valid purpose outside of a
   laboratory setting.
-i wait - Sets a delay between each Ping packet sent.  Incompatible with -f above
   since -f is intended to send packets as fast as it can.
-q quiet - Doesn't provide console output until either the count (-c) is reached
   or the process is interrupted.  At this point, the summary data is output.
-R Record Route - This doesn't work for me, and I've never used it.