I didn’t find a really good way to handle nmap output for larger scans, usually I ended up importing output into a spreadsheet to do sorting and filtering and stuff. To make my life easier, I instead wrote a one-page-app which gobbles up the nmap output xml file and allows you to do all these things on a webpage.
Some info: - Based on datatables (www.datatables.net) and jquery, mustache.js, icanhaz.js
Oh, and you can also find it under Tools. Or, just click here