Message boards and mailing lists allow you to post your inquiries and questions. Such can include requests for information about your ancestors, related genealogy research questions, questions about information sources and participation discussons about locations and events. Just keep your messages pertinent to the theme of the message board (e.g., don't post Plumas County questons on the Sierra County message board).
Posted messages are indexed by Google and other search engines. So what you post will be extremely visible. There are usually experts looking through the new messages which means you may get a high quality answer. And you might hit the jackpot by getting a response from another person who is also researching one of your lines of ancestors.
A message board is, at its core, a vehicle for self-help. If you can, post a helpful answer to the inquiries of others.
Links to messages boards and/or message lists pertaining to Sierra Couny are listed below. If you know of any others, please let me know.