I think he's talking about Quake2, Quake3, Quake4, and ET:QW.
I'm a fan of keeping the rule of "If its Quake and its open sourced in the engine" that seems to be unspoken, my vote is for Quake, Quake2 and Q3A.
Publicity? I'd say just make sure we get it posted on all the major public sites
I will post news of it here - which generally translates to it being news on PQ and QuakeOne as well. It would probably spread from there. However what we need to do more is personally spread news. In the eve of QExpo06, I connected to random servers, netQuake and QW... and played for a while, and would ask people if they knew about QExpo. No one ever did. Not a single player I ran into had heard a word of it before, the closest I ever got was people thinking I was talking about QuakeCon. We need to simply tell more players, a lot of people just play Quake on servers and don't frequent as many sites, they don't keep an eye on community happenings, they just stick to the servers. Find them, offer news of it to them, because you know they will enjoy what they find there.
On still the note of publicity... There are other Quake scenes... the Brazilian scene for example, of which we theoretically have our own ambassador of Orion, and though I am not interested in making QExpo bi-lingual (that would be quite a mess, even for news alone, let alone booths) it could do well to be more international beyond the nationalities present in... ...basically I3D and Func_Msgboard. Thats another thing, we need more activity from content creators outside of these two websites.
For keeping it fresh, I say we should just play some Quake during it... Bring people things they haven't seen before and make them accessible. You know whats damn fun? Storm the Castle. You know what basically no one outside of #qc regulars haven't played? Storm the Castle. Put up a server, or get a server to run it, and make all the files necessary easy to get a hold of (single pak file, straight up readme file, drop it in the appropriate folder and then connect to the server and bam, you're playing). The same can be said for other easy to get into mods (STC works because people who have played TF are immediately familiar, and its not too complicated otherwise), or even just older mods (Zerstorer dm and Painkeep).
Celebrity matches! Frag FrikaC, get a free link to dl Fimg! Granted it is free anyways, but... well.... silliness! Play Quake!
I can poke at Romero about some things as well, I keep in contact with him.
Other than that, I'd say we should see if some id software guys can show up for an event or interview or something.
I can begin looking into this if you wish, maybe get Romero to comment on something in the expo or the expo itself, or try and get a hold of someone else (Carmack, Petersen, McGee, A. Carmack, Cloud come to mind).