I had some issue with Google when querying about current time in different zone. Despite that, it seems too lazy if you can do in your own terminal. date command can achieve that with environment variable TZ, but you need to use perfect match timezone string, which you can found at /usr/share/zoneinfo/posix.

I found an answer of having world clock using a simple Bash script, and I expanded it a little more, the Gist:

If run cliclock.sh testzones cet and testzones file contains:
new york
Los Angeles
A snapshot of output looks like:
US/Pacific           2012-06-14 17:10:57 PDT
Europe/Berlin        2012-06-15 02:10:57 CEST
Chile/Continental    2012-06-14 20:10:57 CLT
America/New_York     2012-06-14 20:10:57 EDT
America/Los_Angeles  2012-06-14 17:10:57 PDT
CET                  2012-06-15 02:10:57 CEST
There are more to improve this script, such as options to add or to remove a zone. You can press Q to quit this script elegantly, so a few more lines should be enough to accept some additional zone since there is already a function for checking validity of input zone name. It can't recognize country codes, but it'd not be a huge task to add a group of zones associated to a country code.