I used to do jetaudio years ago, then some winamp... found VLC finally and then recently KMPlayer. I think it's something like a Korean MPlayer or something, since I thought it was perhaps a windows port of a KDE Mplayer but I was wrong. It is the only player that will play back my blu-ray movies that I ripped to the hard drive, and my god does it have a lot of options. Seems to be in perpetual beta as far as I can see. Otherwise it's VLC... haven't heard of Gomplayer yet, will check it out.
As far as ipod I settled on yamipod right now, it's cross platform, lives on the ipod and it's FREE... I refuse to pay for software left and right.
However my all time favorite mediaplayer would be mythtv... honestly it was like a religious experience once I got that sucker going. TV will never be the same, nor video's, music etc. Absolutely amazing. I broke it once and I honestly feared for my life cause my gf lost her tv, and setting up from scratch was a PITA so I put it off. Mythbuntu is the new heir to my fortune (all $15 or so).