SanDisk's Sansa e250 MP3 player is the 2GB model which not only plays MP3s but also will play videos and FM radio. It has a 1.8" LCD, a lighted scroll wheel, lock, and a voice recorder as well. Battery life is up to 20 hours, a port for microSD cards, and it is highly customizable.
I love my Sansa for a variety of reasons. First off, it requires no third party software. That means you can drag and drop files right into the directory then the next time you turn it on, it will rebuild your master playlist. You can also use it just like a regular flash drive and store data files on it. It can be set in a different mode where it will sync with Windows Media Player if you want it to do that, and you can add files from there. If you want to add video, you have to use the software they provide, as it formats the videos to the right ratio so they can be shown on the screen.
The menus are crisp, clean, and easy to navigate. Sound quality is good. The earbuds are not the best, but if you're a MP3 player junkie you should probably have a set you like already. I recommend Fontopias. The voice recorder works well, but the button is a little too easy to press, so you may find yourself accidentally turning that mode on at times.
Since I got mine as a refurb, the battery was kind of dead, but replacement batteries are cheap (under $15) and very easy to replace. The device seems a bit susceptible to scratches, so if you get it, you should invest in a skin & screen protector (under $10) as well.
The Sansa e200 line (which includes the e250) has support for Rockbox, which allows you to dual boot the device. Rockbox has a variety of nice features including a lot of games and support for alternate music formats such as SPC and OGG.
The Sansa e250 is easily the best value for the most customizable and easy-to-use MP3 player out there. I am very picky about what I use and I really enjoy this player.