list applied Irules for a specified VIP

While all this could be done in fewer lines just as easily, here's some code that should help using iControlRest.

$f5Host = "f5.example.com";
$f5Cred = (Get-Credential);
$prefix = "https://$f5Host/mgmt/tm";
$vip    = "/MY_VIP_NAME";                        You can leave this variable blank to return all the VIPs and their iRules
$resp   = Invoke-RestMethod -Method GET -Uri "$prefix/ltm/virtual$($vip)?`$select=fullPath,rules" -Credential $f5Cred;
$list   = ($resp.items, $resp, 1 -ne $null)[0];  REF: http://stackoverflow.com/questions/10623907/null-coalescing-in-powershell
$list;