A: I really like your shirt. Hasn't Harry got one just like it?
B: Talking of Harry, did he get the job he applied for?

To change the direction of a conversation, but making a link with what has just been said.

So lets meet at five o'clock then. By the way / Incidentally, could you possibly lend me some money until the weekend?

To introduce something you have just thought of, or to change the subject completely.

A: Did you see the match last night?
B: No, I didn't. Actually / In fact / As a matter of fact I don't really like football.

To introduce additional surprising or unexpected information.

We didn't go away at the weekend because I had too much work. In any case / Anyway the weather was awful, so we didn't miss anything.

To introduce the idea that what you said before is less important than what you are going to say. To return to the main topic after a digression.

Yes, it was a bad accident. At least nobody was killed, though. Tom's coming to the meeting, or at least he said he was.

To introduce a positive point after some negative information. To make what you have just said less definite.

As I was saying, if Mark gets the job we'll have to reorganize the department.

To return to a previous subject, often after you have been interrupted.

On the whole, I think that women make better journalists than men.

To generalize.

I like both flats, but all in all, I think I prefer the one next to the cathedral.

To say that you are taking everything into consideration.

I think we should buy them. After all, we'll never find them anywhere cheaper than this.

To introduce a strong argument that the other person may not have taken into consideration.

I don't think I'll come to Nick's party. It will finish very late. Besides, I won't know many people there.

To add additional information or arguments.

Basically, my job involves computer skills and people skills.

To introduce the most important or fundamental point.

Obviously you can't get a real idea of life in Japan unless you can speak the language.

To introduce a fact that is very clear to see or understand.

She's very selfish. I mean, she never thinks about other people at all.

To make things clearer or give more details.

A lot of people booed, and some people even left early. In other words, it was a complete disaster.

To say something again in another way.

Please try not to make a mess when you make the cake. Otherwise I'm going to have to clean the kitchen again.

To say what the result would be if something did not happen or if the situation were different.

That's all you need to know about the travel arrangements. As far as accommodation is concerned, As regards / Regarding accommodation, the options are living with a family or living in a hall of residence.

To introduce a new topic or to announce a change of subject.

The government are going to help first-time buyers. That is to say, they are going to make mortgages more easily available.

To introduce an explanation or clarification of a point you have just made.

On (the) one hand, more young people today carry knives. On (the) other hand, the total number of violent crimes has dropped.

To balance contrasting facts or points. On the other hand is also used alone to introduce a contrasting fact or point.