Hardware & software:
- Plexamp at https://plexamp.com for free from Andy Ihnatko.
- Epubor at https://www.epubor.com for $29.99 from Leo Laporte.
- EatOkra at https://www.eatokra.com for free from Lori Gil.
- Pcalc at https://pcalc.com for $9.99 from Rene Ritchie.