Rune Priests (part 1)

Right, time to look at Rune Priests.

Firstly, their statline.  Its a solid statline, but not much to write home about.  Weapon Skill 5 is nice, but not the most dangerous in the world.  They hit normal marines on a 3+, which is pretty respectable.  They aren't combat characters as such and would struggle without a lot of support.  The rest of their statline ranges from average to better than average (for a marine).
Then we have have their Runic Weapons.  Runic Weapons are force weapons that help you nullify psychic powers on a roll of a 4+.  This makes them better than normal librarians straight away.  Then we have the fact that they wound Daemons on a 2+.  While this is nice, it is very situational (obviously).
So, for 100 points, Rune priests are better than standard librarians even without taking into account psychic powers.

Now lets look at the psychic powers.
Thunderclap
A strength 3 ap 5 large blast touching the Rune Priest.  Not great to be honest, probably the worst of the psychic powers.

Living Lightning
Unlimited range, yes please.  Strength 7, Ap 5 and Assault 6.  I'll take some of that.  Definately a solid psychic power, simple to use and likely to have an effect.  The fact that its range is unlimited means you can outdistance any of the heavy weapons your opponent is using.  This doesnt tend to be a problem unless you are playing a really big board.  My most common use of this power is to assist in destroying light transports that my Grey Hunters can then charge.  With its strength of 7, it can destroy transports upto AV12 and threaten AV13.  With a Rune Priest in a rhino this can really ruin a light mech armies day.

Storm Caller
5+ Cover save for units within 6 inches of the Rune Priest.  Not a bad psychic power, but again a very situational one.  For a mechanised army, probably not very useful as most of your units will be in vehicles or in combat anyway.  If you wanted to run a foot slogging army, then I imagine this power would be incredibly useful. 

Tempest's Wrath
This power has the potential to be devastating against certain armies.  Eldar, Dark Dldar and Blood Angels can really have their day ruined by this.  Against other armies, its really not that worthwhile.

Fury of the Wolf Spirits
Short ranged and an assault power.  Has potential, but isnt overwhelming in my view.  The fact that it causes an enemy unit a Morale check if they even take one casualty makes this power significantly better.  I've never used it, but I can see why it would be used.  This works well for Space Wolves because they are an army that works well at short range with a lot of assault power.

Murdous Hurricane
A pretty fantastic psychic power if you ask me.  A range of 18 inches, further than a pistol and out of the move and assault range of most opponents.  Can deal 3d6 strength 3 hits against the unit is also pretty good, if you roll well enough you could even take down space marines with it.  The really nice part is the fact that it makes that unit move as though they are in dangerous and difficult terrain.  This can ruin an assault units day and mean that your own units have a better chance of getting into combat with them when you want to.

Jaws of the World Wolf
One of the most well known of the Space Wolves psychic powers.  The ability to simply remove models from the game was non existant in this edition until the Space Wolves.  It ignores eternal warrior, cover saves, invulnerable saves etc.  However, its probably one of the more unreliable powers.  There are times that I've been really lucky and managed to take off a lot with it, other times its done nothing all game.  However, there is one thing about Jaws that I tend to find the most useful.  Jaws of the World Wolf is seen as such a scary power to be on the recieving end of that a lot of opponents I've played will really worry about their movement after they realise you have it.  This allows you to start to exert some control over the game, even during your opponents turn.  Experienced players won't always be as easy to trick, but it can be worth a try.

Right, now that I've spoken about the psychic powers, I'll put them in the order of my favourites.

1-Murderous Hurricane
2-Jaws of the World Wolf/Living Lightning
3-Fury of the Wolf Spirits
4-Tempest's Wrath
5-Storm Caller
6-Thunderclap

The main thing I always try to remember about Space Wolves psychic powers is that they aren't so much about damage (which they do pretty well though) they are about controlling the situation.

I hope this has helped, part 2 will have more about equipment and different ways I think of tooling up my Rune Priests.