Many user groups fade away because of low activity. A community only exists when there are enough iteration between the members, therefore it's important to keep it running.
Find speakers is not easy neither. You can start with your local pool, but depending on the size of your city/region you can exhaust it very fast.
Tips:
- As user group organiser, you probably attend a couple of conferences a year. Invite speakers personally whenever you met them at conferences and keep in touch.
- You don't need to have always a rock start or top expert, everybody can talk and share their experiences in your user group. Promote a friendly environment so everybody feels comfortable to talk.
- Keep an eye on conferences happening close to your region, an international speaker may be around. Offer him to give a preview of his talk in your user group.
- Not all events need to be a talk. Hacking sessions or just a beer are also valid user group activities. Why not a barbecue?
- "Bring your scala code events", in this kind of event members show what they have done professionally or only for fun. Works very well. No presentation, only show code to peers. Can be done in a pub for instance.
- Check with Typesafe if they can send you a rock star. :-)