The Common Voice Project by Mozilla reached its first goal: 1k hours in englisch
voice.mozilla.org
voice.mozilla.org
Other languages are looking good too. Germany has almost reached 600 h, French almost 500 h and the website was localized to many other small and big languages in the last year.
The main factor to build a good dataset is A having a diverse group of donors and B having enough sentences. So if you want to help you can either donate your voice, validate other voices or collect more sentences to record. All three tasks are equally important to create a good dataset.