I don't think BBSmart can be used without BES/BIS, can it? This is only a graphical extension for the regular BB mail client and not a stand-alone application if I'm not mistaken.
Gmail app (gmail.com/app) provides almost the same range of notifications as the built-in BB mail client and can be used without BIS/BES. It offers vibration, ringtones, LED - the only thing missing is that little "envelope" icon on the top of the screen which shows up when BIS/BES mail or SMS arrives.
Please note that this is not (yet) true push mail, but the application just polls for new mail every 20 minutes. Obviously, it only works with Gmail / Googlemail. Other stand-alone mail clients come from Yahoo (go.yahoo.com) or TiggIt (tiggit software
) but their notification is not as good in my opinion.