Time and Date functions are very important when writing shell scripts. I mostly use them for logging reasons, for example to know when something was run last. As much as I dislike time stamps they are still used (at least for now) and therefore I am giving and example.
I am unsure of a way to get a time stamp in Bash. If you have PHP installed you can do the following to get a UNIX time stamp (suitable for inserting into a DB):
php -r 'echo time()."\n";'
php -r executes PHP code inside quotes. the time() function just creates a time stamp for the current time. If you need to format a string based on a time stamp you can use the date() function. Here is an example of turning a timestamp into a readable string:
bash-3.1$ php -r 'echo date("l dS \of F Y h:i:s A","1204476759")."\n";'
Sunday 02nd of March 2008 11:52:39 AM
Take a look at the date() function page on php.net if you wish to use this method of using time stamps in the shell.
If any one has any other methods of using time stamps in the shell or needs any help as usual leave a comment :)