Sites of publishers of online (browser-based) mind-mapping software, and sites about mind mapping software generally. For the fullest information on web-based mind mapping and related software, with screenshots, price, summary and links to publishers' sites, please go to MindMapSearch's mother site:
Click here: Mind-Mapping.org. You can use the Refine Software List tab to select 'Mind maps' in the left-hand list box, and 'web based' in the right-hand one. Then press 'Show selected items'.