Well, as a super quick summary:
Black Templars generally like to rush at their enemies head long in very large squads and beat their faces in. Templar armies are generally extremely scary in close combat and will run over just about anything that they charge. The best Templar armies will use the Accept Any Challenge No Matter the Odds vow which gives all Black Templars except the Neophytes (the Black Templar equivalents of Scouts) Preferred Enemy. Templar armies tend to struggle a bit in the shooting department though because of their Kill Them All! special rule which forces Black Templars to pass a Leadership test with a -1 modifier in order to shoot an enemy unit more distant than the closest.
Blood Angels are unique in that they're one of the most mobile Space Marine Chapters there is. They have access to a lot of troops with jump packs and are also pretty fearsome in close combat. Right now, Blood Angels depend a lot on their special characters and Death Company to provide the army with much in the way of hitting power because all Blood Angel units are extremely expensive in points. Brother Corbulo and Commander Dante excel at enhancing the close combat abilities of friendly units around them, where Chief Librarian Mephiston, the Lord of Death is one of the most powerful special characters in the game. He's able to dish out a huge amount of damage in a turn. Blood Angel armies tend to be very small because of their high points costs.
Crimson Fists don't have any actual special rules, but there is one special character in Codex: Space Marines named Pedro Kantor, who is their Chapter Master. Pedro gives the entire army the Stubborn ability and makes all units of Sternguard scoring. This generally means that Crimson Fist armies will have a large number of veterans in the army and can afford to take less units of Troops. Crimson Fists are extremely difficult to move from a position since their Stubborn rule prevents them from suffering from negative modifiers to their Leadership. This means that as a Crimson Fist player you can generally expect your army to stubbornly fight to the last.
The Dark Angels are very similar to a Codex Chapter like the Ultramarines in gameplay, though they do have access to a few special units that set them apart. Deathwing Terminators are arguably superior to the Terminators in Codex: Space Marines because of their Fearlessness, but also because they're able to mix the wargear of a normal Terminator squad and a Terminator Assault squad together into one unit. Ravenwing Bikes are the other unit that sets the Dark Angels apart - these guys are also Fearless, benefit from Scout (allowing them to move before the game even begins, or to Outflank) and carry teleport homers which allow Deathwing Terminators to Deep Strike safely onto the battlefield.
The Imperial Fists are like the Crimson Fists in that they have no special rules of their own and that they require a special character (in this case Captain Lysander) to set them apart from a Codex Chapter. Imperial Fist armies are Stubborn just like their Crimson Fist brethren and many Imperial Fist armies are built to shoot very well, carrying a lot of heavy weapons as well as units like Predators, Whirlwinds and Thunderfire cannon. Captain Lysander is one of the toughest special characters in the game because he's immune to instant death, carries a storm shield for an excellent 3+ Invulnerable save and has a master-crafted thunder hammer that strikes even harder than a normal thunder hammer does. Lysander's only real weakness is a relative lack of maneuverability (like all characters in Terminator armor) and no shooting attacks.
The Raven Guard are somewhat similar to the Blood Angels in that their armies are very quick and maneuverable. Like many other Chapters, the Raven Guard need Shadow Captain Kayvaan Shrike to access any special rules. Shrike gives the army Fleet, which means Raven Guard units will find themselves able to assault earlier than most Space Marine armies. Raven Guard tend toward large numbers of models equipped with jump packs like the Blood Angels do, but are even faster thanks to Fleet.
Salamanders require Vulkan to unlock their Chapter Tactic which twin-links all melta weapons, as well as all flamers and heavy flamers. Additionally, all thunder hammers in an army with Vulkan become master-crafted. This means that most Salamander armies will rely upon short-ranged melta and flame weaponry to do the majority of their damage. All the points spent on close ranged weaponry generally will mean that Salamanders don't have much in the way of long ranged firepower though, so it pays to be quick so you can get into range quickly. Vulkan himself is a powerful fighter. He's armed with a master-crafted relic blade and gauntlet that can fire with the profile of a heavy flamer, wears artificer armor and is protected by a 3+ Invulnerable save.
Space Wolves are a rowdy bunch. Basically everything in the Space Wolf army is extremely adept at close combat and are generally armed to the teeth. Grey Hunters are arguably the best Troops choice in the entire game. They cost less points than their equivalent units in other Space Marine armies and are equipped with more weaponry and are able to take even more weapon upgrades. Space Wolf armies will generally be looking for a fight in close combat as early as possible, so most of their units will be equipped to maximize their potential up close with power weapons, meltaguns and more. The Space Wolves have access to a wide range of special characters all of which are expensive in points but are extremely powerful. The only real weakness of the Space Wolves is that their long ranged weaponry will almost always be mounted on vehicles as the only infantry unit that can carry any heavy weapons is the Long Fangs.
The Ultramarines don't really need much mention here. They operate right out of Codex: Space Marines. Their tactics can be found in basically any Space Marine tactica. Since the Ultramarines are basically the epitome of what it is to be one of the Emperor's Finest, they're generally a very popular army and can easily be found almost anywhere that people are playing 40K.
Lastly, the White Scars are a Chapter that uses a lot of extremely quick units like Bikes and Land Speeders. Their special character allows White Scars units to Outflank, allowing them to quickly encircle their enemies. Since White Scars armies are generally mounted on Bikes, they often have less models on the table than other Chapters. Kor'sarro Khan is the special character of the White Scars, who grants Furious Charge and Hit and Run to any unit he joins. He can also be mounted on a Bike if he wants, allowing him to reach combat even faster.
Hopefully that gives you a rough idea of how each of the Chapters that you mentioned operate on the battlefield.
Last edited by Katie Drake; 01-25-10 at 11:16 PM.