To get expiration date use grep command:

$ whois nixcraft.com | egrep -i 'Expiration|Expires on'
Output:

 Expiration Date: 10-may-2009
NOTICE: The expiration date displayed in this record is the date the
currently set to expire. This date does not necessarily reflect the expiration
view the registrar's reported date of expiration for this registration.
      Expires on: 10-May-09

Here is my script:

#!/bin/bash
# Domain name list - add your domainname here
DOM="theos.in cricketnow.in nixcraft.com nixcraft.org nixcraft.biz nixcraft.net nixcraft.info cyberciti.biz cyberciti.org gite.in nixcraft.in"
for d in $DOM
do
  echo -n "$d - "
  whois $d | egrep -i 'Expiration|Expires on' | head -1
  # If you need list..
  # whois $d | egrep -i 'Expiration|Expires on' | head -1 >> /tmp/domain.date
  #
  echo ""
done
#
# [ -f /tmp/domain.date ] && mail -s 'Domain renew / expiration date' you@yahoo.com < /tmp/domain.date || :
#

Output:

theos.in - Expiration Date:28-Oct-2007 13:01:58 UTC

cricketnow.in - Expiration Date:29-Jul-2008 09:17:56 UTC

nixcraft.com -    Expiration Date: 10-may-2009

nixcraft.org - Expiration Date:13-Aug-2007 14:58:30 UTC

nixcraft.biz - Domain Expiration Date:                      Fri Jun 01 23:59:59 GMT 2007

nixcraft.net -    Expiration Date: 11-dec-2007

nixcraft.info - Expiration Date:26-Jun-2007 11:05:13 UTC

cyberciti.biz - Domain Expiration Date:                      Tue Jun 30 23:59:59 GMT 2009

cyberciti.org - Expiration Date:25-May-2007 11:20:40 UTC

gite.in - Expiration Date:14-Sep-2007 06:47:36 UTC

nixcraft.in - Expiration Date:02-Feb-2008 05:33:08 UTC