I've been running live advice clinics on Twitter for over a year. Whenever I have a bit of free time (at least 20 minutes) I send out a message like this "#prclinic now open for 30 minutes. Tweet your PR questions. All questions answered" The first word (#prclinic) is what is known as a hashtag. It's a way of adding a keyword to a tweet, so that all messages with the same "tag"can be found easily by using the search box.
There are a number of benefits in running advice clinics on Twitter.
1. It establishes you as an expert (provide your answers make sense)
2. It helps the person asking the question
3. It provides you with information about the type of problems people have in your area of expertise
4. It's fun!
Whatever your area of expertise, I urge you to offer advice clinics on Twitter. There's one more benefit too - it will help you to be more concise with your messages, and that's no bad thing.