ESL Conversation cl activities?

Hey all, so I'm currently volunteering as a conversation monitor for a level 3 English as a second language cl. For one hour each week, I need to engage the students in conversation and help them practice their oral skills, correct them...etc. However, what kinds of activities, games, or debates can I organize to engage them in open conversation with each other? Most of the students are between 25 and 40 years of age, and their English is actually pretty good....they mentioned they would like to work on slight grammatical correction in their sentences, pronounciation, and extend their vocabulary. Would any of you have any ideas as to what kinds of activities I could plan to get them to converse with each other, and practice new vocabulary and grammar? If you have any ideas or experience, please let me know!! =)