Ben sent in his nether-go deck for a tune up recently.  What he mainly expects to face is blue/white control, with green/white geddon and black/red void occasionally.  Here's Ben's list:

>8 swamps
>11 islands
>3 salt marsh
>1 underground river (cause i cant get any more)

         You'll probably want to go up to at least 24 land for a deck like this, if not 26.  Your card drawing really isn't strong enough to run less than that.  We'll change it to 25 as a compromise and just add 1 island and one swamp.

>4 accumluated knowledge
>4 recoil
>4 counterspell
>4 undermine
>4 spite/malice
>3 foil
>2 thwart
>2 lobotomy
>2 bribery
>2 dominate

         This seems to be an older version of nether go, and I am a big fan of a newer version that does not utilize lobotomy, dominat, bribery, or thwart.  Here's how I would change the spells:

4 Accumulated Knowledge
4 Recoil
4 Probe
4 Fact or fiction
4 Counterspell
2 Foil
4 Undermine
3 Massacre
2 Cremate

Here's the explanations:
-Probe: Its always a good card drawer, and often, it'll destroy those last two cards your opponent was holding.  From then on, five mana is scary for your opponent.  Also a great way to dump nether spirits and accumulated knowledges, as they're both just as good in the grave.
-Fact or Fiction:  This also dumps cards in your grave, which is always fun, and it also can net insane card adavantage when your opponent doesn't know what you want.  For example, fact or fiction in response to a spell:  your opponent will put a counter by itself and then the other four cards.  You smile and take the four cards and play the counter from your hand.
-Massacre:  unbelievably unfair against rebel decks, and not too bad against fires either, kills birds, elves, and boas left and right.
-Cremate:  Always a cantrip, but often helpful in preventing your nether spirits from becoming useless, also beats opposing spirits, hammers of bogardan, and pyre zombies, as well as yawgmoth's agenda.

artifacts and creatures:
2 Jayemdae Tome
1 thrashing wumpus
3 nether spirit

Lastly, your win condition.  Lets make it look like this:
3 Nether Spirit
1 Avatar of Woe
-The Avatar is funny, but when your opponent finally thinks they've recovered, he jumps down and makes things really ugly for your opponent.

>2 misdirections
>2 war tax
>4 cremate
>2 dominate
>1 thrashing wumpus
>4 massacre

With the changes to the main deck, our sideboard can change drastically.  Here's what It can look like now:

2 Cremate
1 Massacre
3 Washout-absolutely phenomenal against fires, rebels, and occasionally, skies.
3 Perish-self explanatory
2 Blind Seer-gets around moats and circles with ease
2 Teferi's response-beats ports
2 misdirection-rages and counters all get stopped

Hope I helped Ben, good luck, and may the cards be strong with you, see you in a Flash!
-Wally West