mac newbie here, suggest me apps

Hi guys, I am totally new to Mac and I don't know anything. Please suggest me good apps like media/mp3 players, themes, softwares which improves visual experience and so forth.

thanks a lot

ps - if there is anything called must have apps, let me know ;P

Here's a good place to start. http://www.mac-forums.com/forums/switcher-hangout/224636-switchers-guide-recommended-free-apps-download-your-new-mac.html

thank you