I look at this from a lot of different angles, by trade I'm a web dev/ui dev, specialising in Drupal and Android. By night I'm a coder/musician/writer/2d/3d artist. So I guess there are the key perspectives I see OGA from

Artist: 

Currently the submissions section is clunky, I know you are working on this as a priority and I don't know what you've done already but here is what I'd like to see:

   Draft status, I want to be able to save everything I've put in without sending it live, often my uploads take a long time, I want to know that even if the main upload fails or the browser crashes I wont have to fill in all the details and upload all the previews all over again.

 More/better tagging system.  I really don't get the current system, the freeform tags make sense, but the checkboxes are all over the place. They really need to be cleaned up and reorganised. A good breakdown for 2D might be something like:

Type:

Texture, Skin, Icon, Portrait, Background, Concept Art,

But the next section should be determined by what you selected above, so for concept art you might get asked for:

Setting:

Historical, Fantasy, Modern, Sci-fi

And then for something like:

Style: 

Realistic, Cartoon, Stylised, Dark, Anime, Pixel

But for Textures those things don't really make sense, so you would instead get asked for

Material:

Natural, Man Made, Abstract

And then a subsection, so if you chose natural you'd then chose from:

Grass, Dirt, Wood, Stone, Plant

 In this way artworks get tagged in a way that makes sense for each pice of art, rather than trying to shoehorn all art into a common set of categories.  yes, there may end up being a lot of options, but if each individual piece need only ever see a handful of them, then it wont overwhelm the artist while still providing the kind of granular browsing options users are after.

Coder:

 The way I see it I would either come here looking for a project to work on or I would come looking for help on/art for my projects.

In essence this is a job search network where no-one gets paid, but the general process of putting up jobs and looking for work still applies.

 Looking for projects:

Firstly, projects need to be browsed the same way you might browse through games on steam. Pick a genre and pick a style, and once I'm looking at an individual project I want to know what stage each project is at, what skills they have already and what skills they are after, I want a screenshots of their current build, a link to try out the current build, a link to their forum and a link to their sourceforge, most of all I want to know how active they are. If there was some way of measuring the activity of their site's forums (like counting the number of new entries in an rss feed of their forum), that would be really helpful. If I could enter in detals of the kind of project I'm idealy looking for on my profile page, that would be awesome too.

 Looking for help:

 Firstly I want most of the work to done automatically, I'm new, I don't know the ettiquete, I just want a button that says  "ask for help" or "start your project". At which point I'm asked for all the information above, the genre, the style, the skills I already have on staff and the skills I am looking for, then I enter in links for my site, my forum, my sourceforge and images and videos.  Again these pages should have the ability to save a draft at any time before publishing it. When I hit publish I should be given links to an automatically generated forum and the final project page, which has an edit button incase I messed something up.  Once I've done that, I want to be able to browse through people's profiles according to their skills and what kinds of projects they are working on and would like to work on.

User:

 Finally, as someone who just hangs out here, I want to be able to vote on things, reddit style, nested comments, upvotes AND downvotes in additions to favorites. I don't want to clog up the list of things im following  by favouriting everyhting I like, but I still want to be able to indicate what I like or dislike, and I like and dislike a LOT of things.  I know you probably don't want to discourage artists by having their work downvoted, so just don't show votes below 0. Really, it will probably motivate them to make better or more appropriate work anyway. If you could add a simple drop down list of  reasons for the downvote/upvote, that'd be cool to. So I could say "Poor Quality" or "Not Useful",  and conversely be able to rate things as "Good Quality", "Useful" those tags could then be plugged into the views module and spat out as "most useful art" and "best quality art".

 Profile:  This should be my home page, with as many options as you can reasonably throw at it, I'm talking profile pictures, galleries, projects I'm working on, groups i'm a part of,  messaging to other users and anything else you can think of. I want to be checking my OGA account every day, I want to be updating it and customising it, making it mine. That'll make me attached to the site and the community.