When WinAmp came out, it became my default MP3 player and assigned to the task of drowning out noise from outside my office. I was happy and kept upgrading it, but along the way I notice that WinAmp was starting to get rather big. Do I need all that fancy graphics and features? Not really. I usually just turn it on and let it play while I am working or I hop from tune to tune while relaxing with a glass of wine in my hand.
Anyway, I got curious enough to see what other choices were out there and found Coolplayer, a tiny open source MP3 player for Win32. It's written in C and it's binary consists of just one 300K EXE file. Installation? What installation? Just run the EXE. It still has too much unnecessary graphics and I think its memory footprint should stay below 5mb instead of popping up to 9mb while playing (probably to load the active MP3 file into memory) but it basically fits my needs.