We're thinking the pig isn't much fun, since he tends to only go in at the end of the game. The builder and the bubba are more fun, since you get to place them more than once a game.

So here's our "Aggressive Pig" idea, which we've talked about but not played yet. (keep in mind we play with 3rd edition german rules, with Rio Grande rules this doesn't work):

A farm is said to be completed when it can never grow because there are non-field features on all sides of all tiles participating in the farm. If a player has a pig in a farm when it is completed, s/he may elect to pig out.

When pigging out, a player scores her points for the farm (if any), then picks up all her followers in the farm and returns them to supply.

The bonus point for the pig is scored - one per city.

If multiple players might pig out, they decide in clockwise order, starting with the player who placed the final tile in the farm.

I presume that means that you can use the pig again - which would be interesting from a tactical perspective.

One question from the pedant: would you consider the pig-herd tile from The River II to be a valid pig in this case? It normally acts like a kind of neutral pig, so I would have thought it could be used for pigging out, even if the pig itself stays in…

We like this idea and started playing it recently.
Our games have brought a couple more ideas to the variation.
1) As soon as a farm completes, it MUST be scored (pigged out??).
2) A farm is not complete until (a) it cannot grow (as above)
and (b) it has no holes in it (ie similar to a city, a farm must
have a completed boundary border AND it must be complete within
those borders (no holes)).

One implication of this is that if a completed farm touches
an incomplete city, the player must pig-out and s/he does not score
points for the incomplete city the farm borders (the player cannot
wait until the city finishes to pig-out).

I suppose another implication is that only completed farms
score during the game, while any farm (complete or not) scores at
the end.

Anyway, we like the pig-out variation!
thanks,
mike.