Storage Question

Im kind of new to cell phones, good with computer just not with cell phones. I have t-mobile and im looking for a new phone. Can newer cell phones be used like USB flash drives to store small stuff on them? I have a cheap mp3 player I use right now to not only play mp3's but I also use it to store small files like reports and stuff for school and I print and work on them at college. Can I get a cell phone to be able to just plug into a comptuer like a USB flash drive and drag and drop files to them, or do I need software and crap to be able to do that. Obviously if I need software I am not to use it how I want, because I want to be able to just plug in my phone and share files with any computer with USB.