Instead of looking for a tool, there is a very quick and easy way that lets me ping a wild range of IPs to find out which IPs are free and which ones have been taken, using the PowerShell built-in cmdlet Test-Connection.
And here is how:
$iprange = 200..254
Foreach ($ip in $iprange)
{
$computer = "192.168.37.$ip"
$status = Test-Connection $computer -count 1 -Quiet
if (!$status)
{
$computer + " - available"
}
}

Copy the code over to PowerShell ISE console, change the IP info and hit the green Go button. You will get the result within a minute.
I personally really like this block of code because I can run many other things between each IP loop to gather more information about each computer on the network, such as uptime, hard drive usage, etc. But if you prefer a one-liner that gives you a set of simple result, try this.
200..254 | foreach { $status=Test-Connection "192.168.37.$_" -Count 1 -Quiet; "192.168.37.$_ $status"}
Hope it helps.
What parameters would you change to make the top script show active connections as opposed to dead IPs?
taking out the ! in the if line.
if ($status) {
$computer + ‘- taken’
}
Thank you Kent. I appreciate your help.