You want to contribute a review to Realm667? We're happy to hear your opinion and are happy to know what you think about whatever wads are out there!
However, in order to maintain cohesiveness, there is a template that should be followed if you plan on writing a review.

Section: This is what game the mod is for--is it for the Doom quartet? Heretic or HeXen? Maybe it's for Strife or Chex Quest? Whatever iwad the game is for, note it in here.
Title: This is the title of the wad you're reviewing. Of course!
Author: Who made this thing? Not all wads come out of nowhere, despite how much we'd sometimes want them to.
Type: Let us know what this is! Is it a single map? Is it a map pack? Total conversion, partial conversion? Gameplay mod?
Gamemode: What was the primary game mode this was developed for? Co-op play, single player play, or competitive play?
Target Port: This is where things get slightly tricky. It's no secret that we're a ZDoom-loving site, but that's not the only source port out there--take note of what source port the wad was designed for, and note it here. Eternity and EDGE are welcome here, too!
Website: Is there a forum topic where info can be found? Maybe it's hosted on the author's website? Or perhaps there's a fan webpage dedicated to it?
Download: Link to where you can download the mod. An /idgames link is very much preferred, but not required.

From there, this section is where you write the actual review of the mod in question. While we don't have a minimum or a maximum character limit for writing reviews, do try to keep from dumping Ayn Rand on us or from channeling e.e.cummings--try to keep from giant walls of text that take aeons to slog through, and check and double-check your spelling and punctuation for corrections!

There are a few things that are extra-useful to keep in mind as you go through and write a review, however. Please consider the following:
* Please try to keep from reviewing unfinished mods, or mods in beta. As time goes on, your thoughts on it will be obsolete as things are changed, improved, tweaked, or brand new things are introduced, and then it won't be informative at all. Even if the mod has been in progress for a long, long time and looks to not be finished within this decade, please refrain.
* A review is not just your opinion, a review is also informative about what happens in it. Don't just talk about whether it's the best thing since sliced bread or how much it's like getting an erection in a blender of razor blades, talk about the level design or the weapons. Give a short overview of what's actually inside the wad, and let people know what they're getting.
* Likewise, a review is not just an information dump, but is also an opinion. How did it make you feel when you were going through it? Why did you end up feeling this way? Don't just say "The weapons are interesting", but say why are they interesting? You aren't just saying your feelings, you're trying to convince a reader whether he/she should or should not download this.
* If possible, try to refrain from sweeping generalizations, be they positive or negative. Don't simply say "X is the best mod in all time" or "everyone hates that overrated X", because neither of them are true. Talk about your OWN experiences and put them in writing, don't assume how other people will or must feel. The moment you start trying to read your reader's thoughts is the moment you alienate them.

That being said, writing and reading reviews should be fun, so don't feel scared about pouring your heart into it! We're all here for fun, after all, so make jokes! Provide interesting anecdotes! Be silly, or be serious!
Then, once you're all done, post it here for us to all look it over. We'll be willing to provide feedback or thoughts, if it perks our interest, and with luck you'll be able to have it on the official site!

Gameplay: On a scale of 1 to 5, how good was the gameplay? This includes level flow and balance, weapon utility and helpfulness, enemy balance and placement. How well does the content work in play?
Design: On a scale of 1 to 5, how good was the design? Did things look pretty, or did they look clustered? Were the new textures well designed and used well, or did they look like they were done in MSPaint and slapped all over the walls? Did the weapons have smooth animations or did they work at one frame per second?
Heavenly: What was one thing that especially stood out as something especially good?
Damned: What was one thing that especially stood out as something especially bad?

And in this section, down here, you post screenshots. Take screenshots of the game as you go along, and post them in your post along with your review. Please have at least three screenshots, unless the wad is super-short, though more is always welcome.
If you're looking for a free accountless image host, http://imgur.com/ is an excellent candidate.