$list = New-Object 'System.Collections.Generic.List[string]'
$list.Add('foo')
$list
#foo

$d = New-Object 'System.Collections.Generic.Dictionary[string,datetime]'
$d.Add('moonshot', [datetime]'7/20/1969')
$d['moonshot']
#Sunday, July 20, 1969 12:00:00 AM