TL;DR
Request for a list for people who are in COGS and in Bristol over the holidays.
Pros:
A mailing list to organise events for people hanging around Bristol that aren't being bogged down with pesky lectures.

Cons:
Another list to add to the many e-mails per day that COGSites might receive.
Moderation takes time if it's implemented and people are pretty much guaranteed to abuse the list if the list is not moderated.
My solution:
A mailing list pre-fixed with [COGS-Eternals] or [COGS-E] (on the usual COGS mailing list) so the e-mails can be filtered if people wanted to and with a decent amount of warning (maybe two weeks before and a reminder at 1 or 2 days). Or an automated e-mail list and hope people don't abuse it (not holding out much hope here, personally).
Maybe a #cogs.social channel should be created for trying to organise events over IRC. I think it would work if it was used for *only* talking about events, maybe only giving notice of an upcoming event. A moderator (maybe a committee member) could tempban people if they start talking about non-event things. A trigger (like !nextevent) could inform people of the next event or two.
The main bit (this is not meant to be insulting to anyone - this is just *my* point of view):
* SubbyMinx mentions that some people might not be around for all of the holidays. Although this is true, some events might happen at the beginning of the holiday and some might be at the end. Since, two of the holidays are 4 weeks long, I suspect that there won't be many events happening. Even if there's one on every third day in a month long holiday, that's still only 10 e-mails over a month (20 if extra forewarning is used). So, my thought on this is: I don't think it'll be a high traffic list and e-mails are checked pretty regularly.
* SubbyMinx also mentions to use the forum/website blog. As far as I know, only the webmaster has access to the blog - correct me if I'm wrong on this since it'll make this comment useless. With respect to the forum, I check it about every other day compared to about hourly (or more frequently) for e-mails (I fact I have a method that tells me when I've received a new e-mail almost as instantly as I've received them). And so, I think that e-mail is a fairly speedy way of contacting people.
* IRC has been mentioned as a method of communication for short notice events. I think that this is a silly idea for these reasons: if there's no-one paying attention, then you won't get any interest to coming to the pub (or whatever); if lots of people are chatting, then the invite can easily get lost in the stream of text that can be created by all the people chatting; finally: I have tried to invite people out to sunday lunches or the pub via IRC with a success rate of about 1 or 2 people in all the times I've tried. So, in *my* experience, IRC is not a good way to invite people to events with little notice. Not sure of the solution there - phoning may be better - not sure.
* Frequency of e-mails. This has been mentioned before but I'd appreciate an e-mail about fortnightly (weekly might be too often and it would mean more work; monthly might miss out things and might turn into a wall of text). I would like a list of upcoming events for the next month or so, so that appropriate plans can be made. This could be extended a little to cover known holiday events too so that people won't miss out on them.
* Fish-Face walked about IRC. I think that IRC is used as a place to be social rather than e-mails/forums which are more often used to organise events. Short notice events were also mentioned but I haven't had much luck with using IRC to organise events.
* SubbyMinx mentioned that anyone can post to the committee for a message to be moderated and then sent out to the COGS community. Is this true? If it is, who are we meant to post to? The secretary?
* LadyChoc mentions that no moderation is good. In my opinion, I don't think this is the case since I had to specifically tell people not to be rude in the time lapse video. If all the COGSites are allowed free access to the mailing list, I think that it will get abused by some people "for the lulz". This would increase the spam to info ratio for the e-mails and people would rather ignore any mails from that list rather than read the next bit of spam. I could be proved wrong on this but I'm unsure about an unmoderated list.