I'd challenge anyone to show me anything close to 40 Alexa skills that are worth remembering.
I will include 'native' skills in this, as these are my reasons for owning Echo.
1. SmartThings. Voice control of the home is worth its weight in hockey pucks.
2. Todoist. Shopping and to-do lists that build themselves, and spew across multiple accounts across multiple platforms, are a godsend.
3. Google Calendar. Link it to Alexa and Todoist, and your appointments never get away from you.
4. Pandora. Not the most awesomest music app, but for free it's great.
5. Alarms. Love it.
6. Timers. Needs tweaking (such as labels), but is pretty good.
7. Weather.
8. Traffic.
9. SMS With Molly. Will use it rarely, but it has already shown itself as a valuable tool.
10. Hue. Took 12 tries, but it finally is obeying voice commands.
11. BMW Connected. Wife likes telling Alexa to unlock her car.
12. Guitar Tuner.
13. MySomm. I like getting different suggestions on my wine choices.
So there's your 13 skills.
Oh wait, you asked for forty :0