I tried this in bot game, and it worked pretty well. I stacked my Q up to 100 bonus damage before the laning phase ended, and he has really strong ganks. Not to mention if you do it right, at level 11 he can take baron with 3 people if he uses his ult.

Nasus can do baron easy with ulti anyway regardless of if he jungles or not, also you can solo dragon at 6 with just ulti and SS if its farmed enough.

as a solo top lane nasus can achieve 9 damage on Q per wave (just killing the caster mobs with Q) this means that during the entire laning phase you achieved the same Q farm as a mere 11 creepwaves.

By the end of the laning phase nasus should be looking at 200+ damage on Q, and 400+ before the game ends

do you have a build for jungle Nasus, because I want to try it

Jungle Nasus is doable, but slower than more competitive junglers. I also do not believe you that you got + 100 on siphoning strike by the time the laning phase ended.... Did you gank, at all? Because even though the true value of the jungler is to allow the solo to gain money and XP, most people will openly disparage you for not ganking.

Much like several GP jungle videos show, the key to jungling Nasus is to switch targets effectively so your Siphoning Strike can get the last hits. It is very possible, as a good jungler, to farm Q in the jungle.

This, also you can blitz through the jungle just as fast or faster than most junglers. Just have to do it right.
Also the gold farm lets you build some key items that make's nasus really OP, and sadly nasus's Q isn't his bread and butter at all. It's ability to apply -90% attack speed to 1 target, and 35% Attack speed slow to AOE, and is tanky enough to take on 3 or 4 people solo. His Q isn't that OMG special, Yes if you sit unharrassed in lane and get fully stacked up to some 500 bonus damage then its a big help, but not the real focus, and I find nasus's that focus Q die really easily. So many times I have killed fully Q'ed up nasus with no problem. Problem is his Q doesn't stack with sheen, they act independently. Yes it's nice to 30% hit a tower, but not best way to build nasus.

But back to jungle nasus, he is a ganking pro, but you have to focus on wither which if you don't do it right slows your jungling down. Take 1 in Q, then focus wither and spirit fire. Getting Ult when you can.
Kill dragon at level 6 which should be during your first pass through the jungle. Yeap before you ever go back to base you have dragon killed off. Even WW has trouble pulling that off.
I take smite not that it's required but can really speed up a kill and get you going faster at early levels. Once you get 3 or so in spirit fire your able to mow through waves. Noting keeping an eye out for anyone over extended. The second anyone is pushing to far out, go there wither, lead with spirit fire and drop them, with a bit of burst. Having -50% slow and having their resists removed usually enough for your team to drop people. Toss your ult up and eat their health while they crawl.

Build cooldown tank items, and grab a gunblade at some point. End result invincible nasus that tank 5 people and kills at least 3 before going down. Toss a few team mates in and its gg for other team.

Oh and keep dragon dead whenever its up. 190Gold X 5 = 950 team gold. That really adds up if you get dragon 3 or 4 times in a game. Takes just a moment to get him. And if you get jumped you can take care of yourself, to at least finish him off. (another reason to take smite with you, ensures someone doesn't steals your buff from under you.

Although I haven't jungled with Nasus, I can see how he would be good at it; especially ganking with his W. The thing is, just because he CAN jungle, doesn’t mean he should. Know what I mean? This is purely anecdotal, but I feel like you’re Q is going to be much stronger by soloing top & last hitting/farming all day which will help you more end game. I see a lot of Nasus players push their lanes with E and that’s a complete waste in my opinion. I like to get pushed back to my tower, farm my Q & use E to zone out the other champ(s).

I guess it also depends on how you play Nasus. I play him as a tanky DPS that focuses on taking out enemy carries ASAP in team fights. I’ve gotten my Q up to almost 400 (normal game, not ranked) and am normally first in overall gold.

If you do have success jungling, I’d love to hear more about it.

Edit:: Hahaha, it looks like someone viewed this thread & downvoted everyones post. It's hard to argue with that sort of sound reasoning...

I would do solo top as him, but in my elo there are hardly any junglers, so this seems like a viable alternative.

He's a viable jungler, but the problem is not is ability to jungle, it is that he needs massive farm (both in gold and his Q) to be any threat late game, and you don't get much of that with jungle creeps,

He is a very sustained jungler and ganking is so awesome with him because W almost always makes them flash but if they're too extended it won't matter :P

You just have to know when you should play him jungle or play him top lane. Jungle still gets farm on the Q but not as much as afk farm top for 30 minutes would, but he can't lane vs some top champions. He does have insane lifesteal though so if you feel comfortable with laning against high harass champs in top lane just because you feel as though you'll be able to sustain through most of it then by all means go top. He should be top over jungle but he is a pretty decent jungle and amazing offtank. If the comp can use Nasus just see if he would be top or jungle and act accordingly.