Pointed Discussion

Obviously benefits from Doubling Season in myriad ways.

There are also a number of token generators with non-permanent tokens that play well with this card. Minion Reflector, Kiki Jiki, Mirror Breaker, Zektar Shrine Expedition, Nacatl War-Pride, etc. Slap an Elemental Mastery on him and he becomes ridiculous in very short order.

I also saw this card get amusingly huge in a Bant-colored deck featuring things like Hunted Phantasm, Phelddagrif and Forbidden Orchard, plus Leyline of Singularity. When the leyline got removed, the player proceeded to bring out the fliers.

This card + Rith's Charm + Promise Of Bunrei are good reasons to play a creative naya-colored devour deck! :)

Run in a green/white saproling deck with Doubling Season.

Works surprisingly well with Teysa.

Use with Sigil Captain. Gives you two +1/+1 counters immediately to start cranking out 3/3 spirits tokens.

Also works really well with any of the Eldrazi spawn token generators.

guys hey guys training ground!!!!!!!!!!!!!!

The best part about this guy is it only cares about +1/+1 counters, so anything that puts a +1/+1 on it will do the trick, but if you are just going for making this guy massive, then use Heartless Summoning and improve it with Training Grounds
Throw him and Grimgrin, Corpse Born into the graveyard and have a Necrotic Ooze on the battlefield works pretty nicely too.
Use Scapegoat (probably on the Isochron Scepter) along with something ridiculously broken like Endless Ranks of the Dead. If you have have a few of those out, you'll get something in the area of 70 tokens every few turns, and they all bounce, thus leave the battlefield.

This.
One Ashnod's Altar.
One Farrelite Priest. (Or Skyshroud Elf for reuseability, but also adds green.)
One Training Grounds.

And a single token from somewhere.

1. Sacrifice a token with Ashnod's Altar to add {2} to your mana pool and put a +1/+1 counter on Twilight Drover.
2. Use Farrelite Priest to turn {2} into {W}{W}.
3. Use {W} (as the activation cost has been reduced by Training Grounds) and remove the counter to activate Twilight Drovers ability, putting two Spirit tokens into play.
4. GOTO 1.

Voila, infinite {W} and infinite Spirits.

@TAGVoar: Heartless Summoning would kill Twilight Drover and most of your tokens, so I wouldn't reccomend using it. Necrotic Ooze, with both this and Grimgrin, Corpse-born in your graveyard wouldn't be much more amusing than either a Jade Mage or a Sphinx of Magosi, unless I'm missing something. And, from all the cards you mentioned, Endless Ranks of the Dead is actually the less broken one. Seriously, Isochron Scepter and Training Grounds? You might as well throw in a Doubling Season and a Skullclamp. These cards are so combo-able that it's kinda pointless to even mention them.

So, this card. It's definetly a fun one in a token deck. You could either use it to multiply your tokens or just let the +1/+1 counters pile up and turn this into a beatstick (and maybe while still leaving some mana open to make some spirits in case someone points some removal at him). Not to mention all the possible combos with him (just look at most creatures in Ghave, guru of spores' precon commander deck).
Also, with Innistrad and Dark Ascension bringing us a lot of new spirit token makers (Midnight Haunting and Mausoleum Guard, for example), this could be a bombastic (not sure if that word exists) addition to a white token deck, at least in casual.

Just plain silly in a Ghave Commander deck.

Reprint in Avacyn Restored please.

@Lord_of_Tresserhorn:

Ever seen Phyrexian Altar?

One Phyrexian Altar.
One Twilight Drover.
One Training Grounds (or two Heartstones).
One token.

1. Sacrifice one token with Phyrexian Altar for .
2. Use to activate Twilight Drover, making two Spirits.
3. GOTO 1.
__
Infinite Spirits, and therefore infinite mana of any color.

Oh, boy! Fun stuff here. He certainly gets a boost from some time with Geist, and Stitcher's apprentice. And, note that for any token dying he gets counters. Not just your own. Oh, token deck. We'll have so much fun.

Spirit tribal always looks better.

Works obscenely well either against or with Nacatl War-Pack as all his tokens vanish at end of turn giving repeatable pump for the drover