Google/Docs

Text Rotation
=ARRAYFORMULA(CONCATENATE((MID( "Text to become vertical"; ROW(INDIRECT("YY1:YY"&LEN( "Text to become vertical" ))); 1)&CHAR(10))))

= regexreplace( "Text", "(.)", "$1"&char(10) )

If a cell is narrow, then here is a quick and dirty approach. Type the word into the spreadsheet cell with a space between each later.

References:
 * how to make vertical column headers in google docs - http://www.quikstarts.com/Internet/Google-Docs/how-to-make-vertical-column-headers-in-google-docs/
 * How to alter text orientation to vertical in Google Spreadsheet document? - Web Applications Stack Exchange - http://webapps.stackexchange.com/questions/18067/how-to-alter-text-orientation-to-vertical-in-google-spreadsheet-document