There are lots of transactions going on every second – both online and offline. Online shopping alone is a big industry; all these rely on payment systems. Topayment.com is a nice and unique name for that industry.
For WordPress, there’s a massive set of people and activity. Hosting, theme design, plugin coding, development, asset trading, and so on. That’s where WPIndustry.com comes in. If you’re big enough to track these activities, then this is the name that’s enough to accommodate the activities.