How to convert list to one cell with commas?

You can go about this two ways that I can see (there may be more):

Method 1 - Assuming your data starts in A1 and goes down, in cell B2, enter this formula:
=A1&", "&A2

Then in cell B3 enter this formula and fill down to the end of the list:
=B2&", "&A3

The final cell in column B will have your list separated by commas.

Method 2 - Use the following information to implement the ConcRange UDF thru VBA (very simple to use - even I could do it!):
http://www.vbaexpress.com/kb/getarticle.php?kb_id=817

- Moo