Functions

http://windowsitpro.com/windows/create-your-own-powershell-functions

function FileSize3 ($dir, $minSize)
\{
 dir $dir |
 where \{$_.length -gt $minsize\}
\}

Is called like this:
FileSize3 -dir C:\Windows ` ( The back tick continues on a new line )
-minSize 100000