I sometimes have to create rDNS entries for a particular server with a bunch of IPs -- and doing it manually isn't very much fun. The following script quickly creates entries that can be pasted into your zone file, or outputted to another file.

#!/bin/bash
# Script to generate Bind reverse DNS entries
# If no arguments, it will ask for each parameter,
# otherwise, you can you simply call it like:
# script "my description" hostname.com. startIP endIP

if [ ! "$1" ]
then
        echo -n "Enter description: "
        read desc
        echo -n "Enter hostname: "
        read host
        echo -n "Enter start IP: "
        read startip
        echo -n "Enter end IP: "
        read endip
else
        desc=$1
        host=$2
        startip=$3
        endip=$4
fi

count=$startip

echo "; $desc"
while [ $count -le $endip ]
do
        printf "%d\t%s\t%s\t%s\n" $count IN PTR $host
        count=$((count+1))
done

Example:

$ genrdns.sh "my server" myserver.com 82 90

; my server
82      IN      PTR     myserver.com
83      IN      PTR     myserver.com
84      IN      PTR     myserver.com