The majority of tools (asides from the official Debian tools) are designed for discovering vulnerable servers that dont belong to you! The Debian tool is great unless for one reason or another you dont / cant have Perl installed.
Read it here
Kevin Figueroa, Marco Figueroa and Anthony L. Williams reminded me that VLANs and other layer 2 stuff is still vulnerable to many attacks. Most are just Denial of Service stuff that would be detected almost instantly and very easily fixed (although not easily preventable) but the cross VLAN packet injection / snooping made me rethink some of my installations that packet injection / snooping would not be a critical issue but might not be desirable. Bare in mind though that in order to attack layer 2 someone needs to own a box on my layer 2 infrastructure which is much more of an issue!