what next after trilogy?

I beat all three campaigns, and was wondering if there are any additional quests/missions after completing the campaign. I read that there's EOTN, GW Beyond, and some additional quests after Prophecies. Anything else? Thanks.

Endgame instances like Underworld. Challenge missions. Hard mode. I don't remember if the PvP training quests are still in the game.

EoTN, elite missions (Underworld, Fissure of Woe, The Deep, Urgoz's Warren, Domain of Anguish, Sorrow's Furnace, Slaver's Exile), dungeons, Hard Mode missions, GW Beyond, Challenge Missions, PvP, title hunting

Just to be clear, those "additional quests after Prophecies" are the Titan quests and maybe The Villainy of Galrath. And, to add to ultimak719's list, there's The Tomb of the Primeval Kings (but it doesn't give a Hall of Monuments statue when completed).

So yeah, that's pretty much all.

I'd just like to clarify what you mean here by "beating all three campaigns". While it's pretty obvious what you probably mean, and I am not trying to be nitpicky, do you mean that you've beaten all 25 missions in Prophecies, all 12 necessary missions in Factions (there's one "extra" mission in that you at one point choose which of two possible missions to do), and all 17 necessary missions in Nightfall (there are 20 missions available, but your path splits 3 times, so you only have to do 17 to get to the end of the game and "beat" it)?
I ask this because, frankly, that's just the start. Once you beat a particular campaign, you will have access to Hard Mode (which is, gasp, harder than normal mode). This may or may not offer much of a "new" experience - it's basically enemies upgraded with better skills, more hp, and higher levels - but it is something new. As mentioned by others, you still have a whole campaign left to do: EotN.
You can also do the elite missions, though if you're a new player you may find it difficult to find a group for those.
Then there is Guild Wars Beyond, which is a collective name for the free content updates that were released after the release of EotN, and are designed to further bridge the story gap between the "end" of GW1 and the beginning of GW2, such as the political situation in Cantha and who's ruling Kryta. Note that they're comparatively tough as compared to the normal campaigns, but you get some nice weapons for them. The story lines aren't horrible, either - the Canthan one is very 1984-ish - so there's that.
I wouldn't bother with the Titan quests. Generally, they are not worth it: they take a while, and the rewards aren't great.
Hope some of this helps! I'm not on GW1 much anymore, but when I am, my IGN is "Portable Healy Unit".

Just go to Lion's Arch and /dance