Being a GM Scripter, I'm probably biased saying this, but, I'd make all of my most-used scripts Official NG features, with some streamlining of features to be more bandwidth-friendly.
Next, I'd greatly improve on the social aspect of NG, I believe 2012 is the year in which the web will become more personal than we've ever seen in the past, with social networks and the smartphone becoming the new "in" thing. So, I'd make Newgrounds sort of like a social network for creators and indie fans. Though I'd try in every way to preserve the feel that the site has, because NG has never felt corporate like a site like FB or Twitter, and NG wouldn't be NG with that corporate feel.
On the subject of making the site more personal for everyone, I'd launch an iOS, Android, and Blackberry campaign of apps, where users could easily use the forums, chat, publish news posts, and those with video upload abilities could upload videos, etc.
I'd also try to direct some of NG's capital toward's purchasing/partnering with a firm specializing in smart/personalized advertising. I'd change all ads on the site to be more smoothly integrated into the UI and personalized to the user, including the API ads.
I'd make the Audio portal a place where artists could easily organize albums, and develop connections with some producers/publishers to offer some of the best NG Audio artists the ability to pitch their material to audio professionals.
I'd do a similar deal with Movies and Games, develop connections with a network of television/movie/game producers, giving the very best of NG's community the ability to join the professional world.
Also, I'd allow Games to be published in Java, HTML5, and Unity aside from just Flash, to make NG a more attractive place for other indie devs to submit content.
I'd also make a restricted version of video submission available. Formats such as .mp4 could be submitted by every user with a certain filesize cap and quantity per month based on the stats of their other submissions. This way, users' whose .mp4 movies are in high demand would be able to submit them while those who spammed the system would lose the privilege.
I'd have an automated system to track the behaviors of suspected alts to stop abuse of the site.
Open the Lit portal. Including a publisher connection like all of the other portals.
Sharegrounds, a new type of portal specifically for organizing cool or unique content from across the internet that users found while browsing the web.
A Sharegrounds plugin for major web browsers.
Sharegrounds button available for other web devs to put on their sites.
And that's just the beginning, NG has so much potential and a community brimming with creativity. I can say without doubt from talking to non regulars that NG is already making a resurgence, hopefully the staff takes advantage of this new momentum to make this site something big, this is where I got my start as a creator and I want to see big things happen for NG.