Rio Karma and Trekstor Vibez come to mind, as well as Rockbox on any DAP that supports it. While the Cowons play Ogg, I don't believe any of them play Ogg gapless, which, to me, kinda defeats the purpose.
I recommend either a H300 or H100 series player (H320, H340, H120, H140). Not nearly as easy to find as an iPod but it has awesome battery time with Rockbox (many Rockbox-enabled players, such as iPods have terrible battery life compared to the stock firmware). But if a 4-5 hour battery time is okay for you and you prefer a smaller, better looking player buy a 30gb 5/5.5G iPod or a 60gb 5G iPod as these are Rockbox compatible.