Let's say you have a bunch of text cells that you want to concatenate into one cell.
For example, you may have labels for different categories stored in column B.
You want to merge a certain set of labels together, and separate them by a blank line.
Simple, use this formula:
=CONCATENATE(B3,char(10),char(13),B5,char(10),char(13),B7,char(10),char(13),B9)
The char(10),char(13) is the ASCII character codes for carriage return, so this is what creates the blank line.
If you want to reference cells on another sheet (e.g. Sheet1) you can do it like so:
=CONCATENATE(Sheet1!B3,char(10),char(13),Sheet1!B5,char(10),char(13),Sheet1!B7,char(10),char(13),Sheet1!B9)
Sorted!