How to move from one drive to another that's a different size?

I've run into this scenario a few time: I need to replace a drive because I need more space, it's having problems, moving to a new box, etc.

What's the best way to copy data from one partition size to another (presuming the target has enough space)?

What about if it's a different file system (such as ReiserFS to ext4)?

If it's just a new drive on an existing system, how do I ensure I don't need to reinstall to get everything working?

Update - many of the options are highly viable, and I've changed this question to community wiki because I don't think there's a "right" answer.

Clone the drive using CloneZilla, then use gparted to resize it. Keep your old one in case if goes wrong :-)

By the way, this way is free.

The solution I've used in the past is tar. If the partitions are the exact same size and type, you can use dd.

Here's my answer to the quandary:

1. boot using a live cd distro such as Slax
2. verify the partitions you want are on the new drive
3. make sure both the old and new drives are mounted, for example /tmp/driveold and /tmp/drivenew'

4. run from a terminal the following tar command:

   (tar cp --xattrs /tmp/driveold/path) | (tar x /tmp/drivenew/path)

5. repeat for each partition you need to copy

This works for every partition I've ever tried it on (excluding /boot, for which I ensure the partitions are identical, and use dd).