PortablePlayers/SamsungYepp
Samsung produce a range of players, many of which support Ogg Vorbis to a greater or lesser degree.
YP-T6
The YP-T6 is an incredibly small flash player with 128/256/512/1024 MB storage, has a mic and FM radio and supports MP3, WMA (DRM) and Ogg Vorbis. The YP-T6 has problems to play ogg-files created with older encoder-versions.
YP-T7
The YP-T7 has either 512MB or 1GB capacity and supports the same audio formats, which also applies to the YP-F1. It can display JPEGs on its color display.
YP-T9
The YP-T9 supports Ogg Vorbis with firmware 1.50 and higher. The older firmware also supports MTP transfers only. The firmware 1.50 and higher works in UMS mode.
YP-C1
The YP-C1 has similar specs, including Vorbis support; at the time of writing, it seems to be readily available only in Korea and China.
YP-53
The YP-53, a small flash player with 128/256/512/1024 MB storage, mic, USB 2.0 and FM radio, supports MP3, WAV, WMA(DRM), Ogg Vorbis(-q >= 0) with Firmware 1.200.
YP-U1
The YP-U1 is a small (2,38 x 8,78 x 1,35 cm, ~32g) flash player with 128/256/512/1024/2048 MB storage. The player has a LCD b/w display and an integrated accumulator that is charged via USB. It supports USB2.0 and has an integrated USB-plug that can be flipped in and out, so no cable or adapter is needed. Besides Vorbis the YP-U1 supports MP3, ASF and WMA (and directory structures).
YP-U2
The YP-U2 sold in the US (YP-U2J) does not support OGG playback at all, despite what the website claims. Flashing an international firmware for the YP-U2XB allows Vorbis playback on US models (it also turns the player into a USB drive, so that WM10 isn't required to transfer files over. Note that certain international firmwares may remove the FM radio feature or hang the YP-U2J. See the appropriate link below for info on getting a hold of the correct Vorbis-compatible firmware.
YP-Z5
The YP-Z5 is a player with color screen, 1/2/4 GB flash memory, USB 2.0 and MP3/WMA/ASF support. OGG is also supported (firmware versions 1.06US, 2.28US), but not officially mentioned on the manufacturers website.