Rockbox is a free replacement firmware for digital music players. It runs on a wide range of players:

Stable ports Rockbox runs well on these players, has installation instructions, and is supported by the installer:

• Apple: iPod 1g through 6g (Classic), iPod Mini, iPod Nano 1g, iPod Nano 2g
• Archos: Jukebox 5000, 6000, Studio, Recorder, FM Recorder, Recorder V2 and Ondio
• Cowon: iAudio X5, X5V, X5L, M5, M5L, M3 and M3L
• Creative: Zen Mozaic, Zen X-Fi, Zen X-Fi 3 and Zen X-Fi Style
• iriver: iHP100 series, H100 series, H300 series and H10 series
• MPIO: HD300
• Olympus: M:Robe 100
• Packard Bell: Vibe 500
• Philips: GoGear SA9200, GoGear HDD16x0 and HDD63x0
• Samsung: YH-820, YH-920 and YH-925
• SanDisk: Sansa c200, e200 and e200R series, Fuze and Fuze+, Clip, Clip+ and Clip Zip
• Toshiba: Gigabeat X and F series
• xDuoo: X3

Source: Rockbox – Free Music Player Firmware