Whenever asked, my students always list "conversation" as the thing they want to learn most. Of course, they are the same students who speak together in their own languages, and if told to "have a conversation" would just sit there. So if you have a "conversation" class, you have to decide how to make them interested in speaking. What do you want to focus on? What are your students interested in? What would prompt them to speak with each other? Here are some activities I've done--you can pick, choose, alter, and ignore them as you wish:
Conversations about real life activities (returning something to the store, wrong number, leaving a message, shopping, doctor's office, dentist, etc.) They can practice a conversation you give them and then alter it to match their own information as a role play.
Make a lot of questions, write them on cards, give each group of 3 or 4 a pack of cards. One student asks the question, then they talk about it.
Have them interview each other. Write down some of the questions, and explain that as long as they are speaking English, they are doing the lesson. If they go off on a tangent, all the better. A conversation is not , "Where do you live?" "In an apartment." I tell my students they have to ask follow up questions too. I often demonstrate this by having them ask me the questions in the interview, and then follow up their questions with more questions (they are always interested in finding out about the teacher.)
I have picked a topic and made a list of questions they could talk about in a discussion with each other (I usually try to have groups of 3, although 4 can sometimes work, even though it often turns into 2 pairs.) Topics are things like "Food" "Education" etc. I had them talk on one day and then the next day I had them write something about the topic they had talked about. I put their writing on the Internet. (It's at
http://fog.ccsf.cc.ca.us/~lfried/writin ... iting.html if you want to get an idea of the subjects.)
They can do a "show and tell" and bring in something that shows you about their native city or their hobby.
My students are not all from the same language background, and even if they are, they are usually pretty good at not speaking their native language. I have them do a lot of pair work where they have to talk about what to do. For example, I have some two-person conversations of about 13 parts. I write the conversation so that it's pretty clear which part comes after which part. (For example, something that says, "Neither do I." would have to come after something like "I don't like that kind of food." ) I cut the conversation so that each person's part (with the name of who is speaking) is separate, so there are 13 parts. I try to make them somewhat idiomatic, and I explain the idioms or difficult vocabulary before they start. Then I have them put the conversation back together working in pairs.
Well, that's some of it. Maybe you will get an idea.