What are some alternatives?
When comparing phpSitemapNG and WonderWebWare Sitemap Generator, you can also consider the following products
DYNO Mapper - Create Sitemaps with the DYNO Mapper Visual Sitemap Generator.
XML-Sitemaps.com - Free Online Google Sitemap Generator.
GlooMaps - Create your visual sitemap on the go - easy peasy
A1 Sitemap Generator - A1 Sitemap Generator has been in active development and sold since 2005.
FlowMapp - UX planning tool for creating a visual sitemap
Moz - Backed by industry-leading data and the largest community of SEOs on the planet, Moz builds tools that make inbound marketing easy.