return {expression}

is equivalent to

    {expression}
    return

the only place you have an exit from a function, script block or similar is either at the end or at a return statement. Every value that isn't assigned or piped into nirvana gets pushed to the pipeline. I actually can't remember having used return statements more often than once or twice so far (and I use PowerShell daily, heavily).

Then I rarely found the need to use ArrayList. Sure, you can use it, but you can just as well do

    $array = @()
    $array += $item

A personal pet peeve of mine is actually that lots of people write PowerShell very similar to equivalent VBScript or C# code. And that makes for horrible PowerShell code (in my eyes). The pipeline is immensely powerful and not using it often makes for pretty crappy code.