Hi
Is there any default/open source snmp application to
send traps
monitor some processes in Solaris
has MIB package available
that can be used in production environment
I am using
SunOS Server1 5.10 Generic_142910-17 i86pc i386 i86pc
If it has a GUI its a plus 
I think the snmp package has command line stuff, but you might want to start with a GUI: snmp gui XWindow OR JAVA OR PERL OR solaris - Google Search
It looks like PERL has the most SNMP batch support: snmp batch OR script OR shell JAVA OR PERL OR solaris - Google Search
Gui is nice, but batch is good for sending alerts via email, pager, SMS and providing CGI web pages for less sophisticated users to review SMS status vs norms. Collecting history with a cron batch might support a nice extension of that web site, using an RDBMS.