Cloaks you can't buy.

As with any melee dps class your bread and butter as a rogue is your time spent damaging the boss and or adds in a fight. Your cooldowns are designed to help you do this and if used properly will usually yield better results in raid performance and may even make the difference in whether or not your group downs a certain boss. Though I'm committed to my assasination gear and spec over combat for boss damamge I am forced to concede deafeat in that combat rogues have much better cooldowns and burst than assasination. There are a few cooldowns that are not from talenting however that are generally overlooked when raiding. Probably the most useful cooldown a rogue has is cloak of shadows. It has a relativly short cooldown and a wide variety of applications. The effect of the ability is that it will remove most harmful debuffs from you such as heavy magic DoT's or things like lord jarruxxus legion flames. There are a few debuff's that have effects that activate once the debuff duration has ended and cloak can activate these so be sure to read up on what you're cloaking out of. The other practical applications for cloak are that it will get you out of snare and root effects as well as magic/poison debuff's that slow you. This can be used to increase time spent on a boss an example would be the jormunger encounter of northrend beasts (paralytic toxin). The final application of cloak is the temporary buff it gives after use in addition to removing your debuffs it will also grant you 90% spell resistence for a short time. This can and should be used should you find yourself in a position where you have to move through fire or stand in an explosion. (lord marrowgar or emalon the storm watcher). Sadly cloak will not get you out of bleed's or physical debuff's and the only way it would ever help with those would be to glyph it for the 40% physical damage reduction, but seeing as the glyph is a major instead of minor there are better ones for the slot. So if used properly cloak can increase you time spent on the boss, survivability in a raid, and in general let you ignore things that would othewise ruin your raiding experience.