- Typically people are now willing to provide an email in exchange for valuable content including downloads, help docs, blogs.
- Medium.com is a great example (which ERPNext folks use and keeps asking me for sign up or sign in).
- So there is no shame in putting a login wall or asking for email id or asking to subscribe in exchange for content.
- This is a big part of the inbound strategy (Marketing strategy), which we should follow.
Again, people come to the foundation because there is something useful.
Ask for an email address & promise them updates when new features 
So floating is not such a bad idea.
Call to action wordings :
Inform me when new features are added : [email address here]
Call me, would like to know more: [email address here]
I love open source, I want to donate, contact me: [email address here]
I want to be a foundation member : [email address]
Send me white papers : [email address]
Send me customer reference : [email address]
Send me when new videos are released : [email address]
Footnote : [leads to subscription of news letter]
Make A/B testing. So use different words for “Call to Action” and see which one performs better
It is trial and error.