Great info, guys.
I am very glad to see technical discussion going on around here (along with people explaining these things so others can learn, instead of bashing those who are not @s into this @s some of us).

Custom subnetting can be very effective for:
- creating smaller collision domains
- increasing security (smaller broadcast domains)
- organization, optimization, and to some extent, more efficient use of your network (though some ip addresses are lost, as the HOST portion of each subnet is a -2 to the total addressable valid ip addresses (because all 1's and all 0's may not be used).

I would be very glad to contribute and discuss deeper networking concepts if others would be willing to get involved also.

(what about cisco ccna, net+, a+, mcse training / related discussion here @ antionline?)