Of the various modes and flavours of collaborative conlang projects I've
seen I have a particular weakness for the diachronic style: i.e. the
initiator creates an ancestral language, and other participants choose one
of the extant langs in the project and derive a daughter.  
Examples I know of are
* the Arda-Lang project initiated on this list, floruit summer 2001, ;
* Pete Bleackley's ConlangEvolutionExperiment on the Talideon Wiki, 2005?,
which has gone down;
* the Akana project of the ZBB, : a later agglomeration of
a couple projects, one played by these rules starting 2006, the other a
reconstruction challenge from 2005.  Still going strong, a dramatic success
by collaborative conlanging standards.

The thing about these, though, is that writing up a whole grammar -- taking
a turn, if you will -- takes a lot of time and effort.  It's enough effort
that I never finished my fourth and most elaborate turn in the CEE (though
IIRC what remained was just a matter of pushing the lexicon through), and
likewise A:jat he-Heloun, my nearly-finished language of Akana, has been
receiving rather little of my attention since my initial burst of steam ran
out some six months into it.  

So, I've been thinking, it'd be cool to do a collaboration of this form
where the turns can be smaller.  (Perhaps is small-scale
precedent for such a thing.)  In outline I envision this:
the current grammar and lexicon &c of the (each) project language is kept on
a wiki; anyone is free to come along and make an edit, of any size,
dictating some diachronic evolution of the language.  And we'd see where it

Anyone else like the sound of that?  Is this an opportune time to do it?

For that matter, anyone have any good ideas as to how to make such a thing
run smooth?  One reason such a project might fail is if it became too
arduous to make a single simple change to the lang and keep everything
consistent.  For instance think of sample sentences and texts: you may not
be inclined to go through and tweak every one of these which your change
ought to effect, and thus they'd gradually fall into disrepair.  What to do
about that?