Iomega 500GB external not recognised

[codenamecueball]

I have an Iomega 500GB External Hard Drive, containing a Seagate 7200.11 (ST3500820AS).
The drive spins up, and gets going, but is not recognised at all by my Mac or my laptop. It contains my entire game collection and a lot of irreplaceable stuff. I don't have a SATA machine handy to test it on, or any SATA cables actually. What can I do?

[editline]19th November 2010[/editline]

Odd, it appears in disk utility, but will not mount:

[url]http://cl.ly/3Jue[/url]

[editline]19th November 2010[/editline]

[img]http://f.cl.ly/items/2A3S0n2I382m3B1l3f38/Screen%20shot%202010-11-19%20at%2011.13.30.png[/img]