Even though Google Apps Standard free version is discontinued but, still user who had account before December 6th, 2012 can get Google Apps for free for new domain names by adding them in existing app account.
Update Note: Google has recently disabled addition on new domain.
This is not any kind of trick, but it is simply adding new domain name to existing Google Apps account. Hence it will get your new domain name active with existing standard Google Apps account.
You can add almost unlimited domain name, but you can manage those accounts by limited 10 users only.
After adding each domain name to existing Apps account, you have to verify each domain name using its verification methods. I prefer to use HTML verification method, because it is quick simple, fast and easy.
Once you added the domain name you can use that account to log-in into your new account.
Suppose you have existing domain attached with standard Google Apps was xyz.com, and you have added abcd.com to this account. Then your new domain log-in for apps URL can be: https://www.google.com/a/cpanel/abcd.com/
So this can be separate Google Apps control panel in existing standard account.
Note and Conclusion:
Now registration for new Apps account are chargeable with some decent price as Google Apps for Business. But if you already had standard account then you may take benefit of using it free.