Rock Band - Rock Band is a Rhythm Music and Single and Multiplayer video game created by Harmonix and published by MTV Games.

BillGrid.com - BillGrid is an easy to use online invoicing, billing and expense management system that will save you time with tracking clients projects, expenses, invoices and payments.

StepMania - Rhythm game for Windows, Mac, and Linux.

ChargeOver - ChargeOver automates recurring billing, subscription billing, & payment acceptance. A SaaS that integrates with Xero, Quickbooks, & has an API. Free trial.

Osu - Osu is Music, Rhythm, Single and Multiplayer video game developed by Dean Herbert.

Elorus - A super-easy online invoicing & time tracking software