SuperCheats.com have now published their guide to Metal Gear Solid 4 and Metal Gear Online.

There is a complete walkthrough, details of all the unlockables and some hints and tips.

The guide is accompanied by screenshots from the game and in-game videos.

It's free to look at, and there is a printer friendly option on all the pages.

The guide can be found here:
http://www.supercheats.com/guides/metal-gear-solid-4/

These become unlocked depending on what stage your 'Game Save' file for Metal Gear Solid 4 is. If you have a 'Game Save' file of a completed game ALL the music tracks will become unlocked. Boss tracks will become unlocked when you have a 'Game Save' file after you have defeated them. If you have a completed 'Game Save' file and continue it in Metal Gear Online ALL the music tracks will be lost until you unlock them again.

If you want the following ranks to appear next to your name when you play Online then this list will help you get it.

Bee Rank:
Use plenty of scans.

Crocodile Rank:
Very good kill death ratio.

Rat Rank:
Continuously get trapped.

Sloth Rank:
Continuously get shot in the head.

Snake Rank:
Perfer sneaking missions.

Turtle Rank:
Use the Cardboard box a lot.

Dove Rank:
Perfer non lethal attacks.

Eagle Rank:
Have a large percentage of headshots.

Flying Squirrel Rank:
Have a high percentage of rolling.