Look also at Rio's Forge 256, another sports-specific flash-based unit with the same easy packability, selling for a marginally pricier $170. With that you also get the capacity to record radio files to your player, though. Want to catch that Terri Gross interview you missed with Philip Roth as you're exploring the Adirondacks? No problem.
A similar unit to the Rio Cali is the Creative Nomad MuVo TX FM 256 ($169, www.nomadworld.com), which is a digital unit that runs off a single AAA battery (Creative bills one battery as good for 15 hours). Storage capacity is basically on a par with the Cali. It looks more like a mini tape recorder (or iPod, for that matter), whereas the Cali or the Forge have more stylin' lines.
Lastly, SanDisk's slimline MP3 ($200) has a rather substantial one gigabyte of storage, so you can load up to 16 hours of MP3 tunes on it, which is in the order of around 240. And it runs on a single AAA battery, so it's easily re-powered. So, tough choice—Rio's snappy, compact styles, SanDisk's storage... I think it'll come down to your budget—the above cost less than the iPod Mini ($249), all are more trail-worthy, yet they will also pack less of your CD collection with you on the trail.
MP3 players and other electronic wizardry reviewed in Outside's 2004 Buyer's Guide .