With over 40 active collectives on the scene, a significant chunk of the most visible comics have been collectivized. Stalin would be pleased.
I've been studying collectives of various types for years, and I have a keen interest in webcomics collectives. (I'm in one.) I want to understand why people join them, why some succeed while others fail, and whether it's a good idea to be in one.
Traffic and peer contact are the main drivers of collectivization. People team up to increase their audience, and to talk with other comics people about comics stuff. They also come in handy if you want to split the cost of a table at a convention.
The increased number of collectives, is, I think, a result of the increased number of webcomics. It's possible that in this larger crowd, people are seeking to form groups as a way to stand out, but it may just be proportional growth.
Having the major hosting sites ComicSpace, OnlineComics.net and WebComicNation in merger-related disarray has probably helped. People may not want to cope with those outdated sites and slow servers. But that's just a hunch.
The performance of collectives varies wildly. Some are among the biggest webcomics sites while others are barely known. See the Directory of Webcomics Collectives for a list.
My observations suggest a successful collective is half do, and half don't.
The "do" is, have a well-designed site with good comics, including, if possible, a fairly popular one. Also have a dedicated webmaster and a subtle, wise forum moderator if you have a room. Comics that look amateurish should be prepared to explain themselves or go elsewhere.
The don't is mostly this: don't leave outdated, non-updating or dead stuff in public view for more than two seconds. It will kill you. A good example is Lunchbox Funnies. They're one of the best designed sites, but half their comics are on hiatus, failing to update for months on end or dealing with delays. Comics are a lifestyle choice, and if you wander off and disrupt the rituals of your readers, they will drop you. Without immediate action, Lunchbox is probably doomed.
Another "do" is, you need people who are at ease communicating with email -- people who read it often, respond immediately and clearly, and don't come away winded. The quiet types -- about a quarter of us -- add little to a collective unless their comic is blazing.
A recent insight that's proving true is that the collective should include comics that update so that every day of the week is covered. This encourages the daily visit ritual among procrastinating job holders.
Having someone in charge of receiving house email, placing ads, and networking makes a big difference. Their name and email should be clearly displayed. They should love doing it.
Returning to my question -- should collectives link to each other -- observation tells me that best practice is to link to ones you respect if they respect you back. Where there are grownups in charge willing to provide mutual support, there is fertile ground for linking. Otherwise you are dealing with the school classroom before the teacher arrives.
Expect the Collectives Directory to start stating the health status of listed collectives in the near future, making it a good way to see who's worth visiting instead of simply who else is out there.