I know a popular idea is starting a new server from scratch; I know I'd enjoy it, but I think those people who have played the same toon for 10 years now shouldn't get the shaft on a 10 year anniversary.
Some ideas that will help the overall game, and can't be QQed about are:
Outside of game:
--> Better customer support.
--> Actually acting on people who break the rules of this game, and eliminating them.
--> Additional CSR support.
--> Herald (which is inc) fix.
--> More player to Dev communication: the most interactive people involved in this game seem to leave shortly after joining the DAoC team. There's no reason why SWTOR (a game that's unreleased) can get a random update or stupid "hey look at this" video several times a week... but we get a single line of text every few months notifying us of A) and update B) some transfer C) Some seasonal D) Some useless information about someone joining the team (which is okay... just not when it's the only thing you post in several months).
--> More updates on "this is what we're looking at" kind of thing.
In game:
--> Relic, Realm and Population adjustments. If your realm owns several relics, owns half of each warmap and has more population than both the other realms put together, add in realm point penalties, nothing huge, just like 25-10%.
--> Old Zerg icons, so if you see a massive hammer on your screen you know there's a mass of mid numbers in this area.
--> A secondary "must have" armor/weapon set. As someone said earlier, perhaps deep in DF, adding additional strengths and abilities to the monsters. However, having the chance of dropping Demon Forged weaponry that is near par with ML10 if not par with ML10. Would also help in spreading zergs around, so there's not one concentrated zerg up at all times, but instead maybe two of smaller numbers.
--> Adjustments of a few classes that require some additional love, debuff of certain classes that require it (based on in game play of devs, and not based on QQs on the VN or in game).
Edit:
Forgot to add in about Hybrid templates; Hybrids are meant to be a bit of a pain to template, if you could 10 your ToAs and 101 all your important stats, hybrids would be top dog (which is funny because most hybrids are already pretty beast).
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Davolica, Fru Norsewoman Warlock. AMO Officer
Hayziis, Bantiarna Lurikeen Mentalist. GM Aes Dana
Macrina, Phoenix Knight Briton Cleric.
http://www.boandterri.net/winlok%20guide.pdf <-- My Warlock Guide