Guild Wars: PvP Unlock Packs
$10/profession for full skill unlocks on that professions... for Prophecies only. $40 for all 6 Prophecies professions.
Update: my random thoughts on this.
This seems most relevant to people who bought Factions, liked the PvP but then were faced with another PvE marathon to get the Prophecies unlocks. I didn't see a requirement to own Prophecies, so instead of spending the $40 on the game they can cut to the chase and just get the skills.
Update: apparently you may have to own Prophecies too right now, which does seem a bit expensive.