Newer files
ls -Recurse | where { $_.LastWriteTime -gt (Get-Date).AddDays(-30) }
# list files newer than 30 days
dir -Recurse | Where { $_.LastAccessTime -gt [DateTime]'2013/05/15'}


Older files (just change gt (=greater than) to lt (=lower than)
dir -Recurse | Where { $_.LastAccessTime -lt [DateTime]'2013/05/15'}


Remove brackets
ls | % {Move-Item -LiteralPath $_.Name $_.Name.Replace("[","")}
ls | % {Move-Item -LiteralPath $_.Name $_.Name.Replace("]","")}


Rename files
dir | Rename-Item -NewName { $_.name -replace "-part-name.","." }


$a = ls
$a | % { Rename-Item -Path $_.pspath -NewName ($_.name -replace "_resize.",".")}