I am currently using Nokia 6630 and 3 applications that I most use on my cell phone are:
1. Opera mini — The fastest and the powerful browser for Symbian 60 serious.
2. FS Caller.
3. Nimbuzz / free download — This is an ultimate software for mobile phones(which has internet connection). This software is an all in one package. You can stay connected to your friends using its Orkut, Facebook, yahoo! messenger, Skype, Windows live messenger, Gtalk, AIM, ICQ, Jabber etc. And you can call, chat from mobile to PC with anyone(who has this apps on PC) and anywhere. Its camera(webcam) feature is an ultimate thing I have seen so far, in a mobile software. If you have a mobile with internet connection, then do not miss installing this software. And happily it costs nothing. yes its a free to use software.
And I use some more common software like FileMan, SmartMoviePlayer, and very few games. And I am not a big fan of music players, as the music files work perfectly in my default player of Nokia 6630.
I will be online most of the times using my mobile, using Opera-mini. I usually visit many blogs and read articles regularly using my mobile. When I am in front of my Computer, I concentrate only on writing articles. And I visit and read a few, selective blogs from my computer.
These are some minimum things I use in my mobile.
I know that, there are people who make use of many applications in their mobiles. If you are one among them or if you know any application, that you think will be useful for others, if you share it here, then please share the information and the link to get the application in the comment section. It would be appreciable, if you also share, how you make use of those applications..