What are some alternatives?
When comparing FlowMapp and XML-Sitemaps.com, you can also consider the following products
Really Good UX - A library of screenshots for UX inspiration
DYNO Mapper - Create Sitemaps with the DYNO Mapper Visual Sitemap Generator.
VisualSitemaps - Autogenerate visual sitemaps in seconds.
GlooMaps - Create your visual sitemap on the go - easy peasy
WonderWebWare Sitemap Generator - Sitemap Generator is freeware program that will help you to automatically generate site maps for google, bing and yahoo in their respective file formats.
UX Recipe for iOS - Design checklist & estimation tool for your next UX project