This has been talked about LONG before you signed up.
I was attempting to code something over the summer like surplus, but school came and I just never had the time.
We have a thanksgiving break 2 weeks from now and if I'm not going anywhere, I'm going on a coding spree. This was one of the projects I was looking at restarting.
Really the only two things I'll have problems with are bandwidth and searching the database. The database will consume massive amounts of bandwidth because I can't find a way around a tag based system that can efficiently find tags. My plan was to put them into an array and store the array as a generic value (ie: "tagcloud") in the table, but in order to search tags, I would have to go through and explode each individual tagcloud in the table. When we get a large amount of mods, this could become particularly troublesome as far as bandwidth consumption goes.
The only way I could see as far as optimization goes is to maybe store the tagcloud using the first letter of the up to 5 words you pick for your tags. So explosion, gun, flak, cannon, ball would be stored as "EGFCB". This way, I won't have to go through and load explosion, gun, flak, cannon, assign a temporary variable for each, read each variable, determine if the variables contain one of the words being searched for, and then tell the script to display the mod or not for each individual mod in the database. Searching for the first letter of the words that are being searched for in the array variable without exploding it should be much more efficient. It will still try to read wrong answers (someone searching for Grenade will try to read the imaginary weapon I listed above), but its a heck of a lot less bandwidth consuming than trying to read a bunch of different, unsortable values from a variable.
I could make the framework if you have the space and bandwidth. You're free to use my idea if you are going to start from the ground up with an original content management system.

Here's what i've been working on right now, besides trying to master php.

DO I SPY FREEMIND?
If not, and you paid for this... RIP OFF! (Freemind is a free mind mapping software for generating charts like the above.)
Also, I much more prefer .PNG as a file format because it is lossless and looks good for most pixel based games. Plus, it is small.
I've done a lot of the back end planning in my mind:
Using PHP, there is a file upload command which should suit my purposes. This will upload into a folder that is something like domain.com/mods/(modnumberhere), where modnumberhere is determined from the current mod number (if there were 53 mods when you uploaded your's, your's will be 54). Simple enough. Then all relevant files will be uploaded into there: .zip/.rar, images, etc. The user will pick an image to be displayed as the "primary" image which appears when you search for mods (similar to garrysmod.org), and PHP can overlay text on images, so (also similar to garrysmod.org), we can overlay a download amount, rating, name, and other information on the image. Tagclouds, as I said, will be stored as arrays in a mySQL table, as well as other information to be loaded about mods. The table would have something along the line of these rows: ModNumber, Name, Tagcloud, File, Images (probably an array also, so users could put many images up for use or random selection from a number of images), Author, Rating, and Downloads. The search engine will search the Tagcloud and Name rows for the relevant strings, then when a user clicks a mod, it will load all the information from the table and display it.
Simple enough, just gotta get tutorials on how.

Well it was freemind, then I switched to an online solution. I'm good with picking software. Anyone care to help me figure out a domain name now that I'm ready to buy the webspace. I'm thinking ccmods.com

face.rape.com Alternatively, CortexMods.com Or be cool and hip and name it ModCrate.com

CortexCommandMods.BRING-BACK-THOR.com
jk.
but really. COME BAK THOR!!!


CortexCommandMods.com

Hmmm... ModCrate.com is pretty good.
You could play off the fact that all this is an extension of a brain and name it accordingly. I'm not creative enough to come up with an actual name, though.

ccmods.com is perfect

Its short, and easy to find.

agreed!

I bought the web space. I've been trying out both php w/ mysql and joomla. I was suprised at how useful joomlas management features were for it. It acts more like a cross between yahoo directories and moddb than joomla. Though the bandwith went much higher than as opposed to the php. In any case, I'll need a few people to help me test it out and give suggestions. They are both very close to completion. by the way. If anyone's interested, PM me.

oh and I bought the webspace under a different domain name but, I'll be purchasing modcrate.com soon. (damn good name, ) thanks for the help with that. and ccmods was purchased from an url squatter, by another one I assume.