How to get a list of all activated features for a site collection and a sub site in SharePoint 2010 using powershell

To get a list of Site collection features:

Get-SPSite http://sharepoint2010 | % {

    $results = @()

    Get-SPFeature -Site $_ -Limit All | % {

    $feature = $_; 
        $featuresDefn = (Get-SPFarm).FeatureDefinitions[$_.ID]; 
        $cc = [System.Globalization.CultureInfo]::CurrentCulture;

        $obj = New-Object PSObject;
        $obj | Add-Member NoteProperty  Title  $($featuresDefn.GetTitle($cc));
        $obj | Add-Member NoteProperty  Hidden $($feature.Hidden);
        
        $results += $obj;
    }
    $results | FT -auto;
}

To get a list of features for a sub site:

Get-SPWeb http://sharepoint2010/subsite | % {

    $results = @()

    Get-SPFeature -Web $_ -Limit All | % {

        $feature = $_; 
        $featuresDefn = (Get-SPFarm).FeatureDefinitions[$_.ID]; 
        $cc = [System.Globalization.CultureInfo]::CurrentCulture;

        $obj = New-Object PSObject;
        $obj | Add-Member NoteProperty  Title  $($featuresDefn.GetTitle($cc));
        $obj | Add-Member NoteProperty  Hidden $($feature.Hidden);
        
        $results += $obj;
    }
    $results | FT -Auto;
} 

Shows both hidden and non-hidden features

Thanks to  Joe Rodgers (blogs.msdn.com/b/josrod/archive/2013/01/04/

powershell-to-list-activated-features-for-a-site-and-web.aspx)