Pelgrane Press' 13th Age is worth buying, even if you do not have any intention of running it. Why? Because you can basically use it as a huge book of house rules and tweaks for 4e – which is exactly how I see it.
I love 13th Age's rule for “skills” - or rather a lack of them – the use of Backgrounds. Much as I love 3.0 / 3.5 and 4e skill systems, they have somewhat taken from the players need to be creative with how they are using them (although I have been a lot more insistent on knowing how my players intend to use the skills they have suggested in a given situation). The background rules, whilst they raise a few issues in 4e (for example, the skill related boons from 4e backgrounds – my answer, apply the bonus when it seems relevant, which shouldn't actually be hard at all), truly encourage the players to think about their character before they became an adventurer, and serve to not only flesh them out, but lend themselves to far more creative use of "skills" in play.
My personal preference for player backgrounds would be to work with them to create them. However, here are a bunch I have come up with to get creative juices flowing...
So, avoiding the more obvious ones...
Unified Order Mage; You have attained the rank of “mage” with the Unified Order, and enjoy the privileges that go with that status. However, you are also restricted by the Order's laws, and as such, are somewhat hampered in your freedom to practice magic.
(Variations with slightly different applications could include Unified Order Artificer, Unified Order Hunter, Unified Order Apprentice, Unified Order Specialist [as in Evoker, Conjurer, Fire Elementalist etc]).
Unified Order Apostate; The Order are a corrupt group of control freaks, who seek to stifle magic, kill the Gods and rule all creation. You have escaped, but they do not want you to live. It is only by your cunning and skills in arcane lore that you have escaped them...so far. (Variations could include, Failed Unified Order Initiate, Subject of Divorcement, Enemy of the Unified Order).
Dundorin Merchant; You were raised in one of the great Karrag's of your people (you will specify which and where), and learned the basic skills and lore taught to all. However, your destiny lay not in the sweltering forges or deadly deep places, but out in the upper world, engaging with the other races....and more importantly, their wealth.
Scarred Veteran; You fought in the (insert war relevant to campaign timeline and setting), and survived despite the horrors you endured, and have carried more than physical scars into these times of relative peace. You struggle to cope with the nightmares and still react to many circumstances as if you were in battle. However, you remain sharp and your wartime skills are still alive within you...even if sometimes they hamper rather than help.
Xix Touched: He whispers to you in many voices, telling you the truth and telling you lies. He picks away at reality, showing you glimpses of the truth beneath, and keeps you safe from those that wish to harm you (or does he?). Amongst other things, you are special, and they know it too.
Bruiser: The North Republic Guard (or Bruisers, due to their black and blue livery) protect the huddled masses against the dangers of the peaks, the lowlands and their own streets. Steadfast and determined, they are the line between the murderous Gorgoth and Gigorim, the Dracane and the manifold other dreads that would sweep down and crush the cities of men.
Tribe Athlete: In a society of natural athletes, you were one of the best.
Risen Lands Botanist: The vast, magic scarred realms of Eathoran and Anathar called to you since you were young, and on arriving you were amazed at the mass of strange, beautiful and at times, deadly flora there. Before you took on the mantle of adventurer, you spent a lot of time studying these plants, and came to know much about them. (Possible Variants could include a specific study of a certain type of monster from a certain type of terrain, so Boreal Aberration Specialist).
Vengeful Barkeep: Once you owned an inn, and life was good. Then (insert catastrophe, organisation or monster) happened, and you lost it all. You remember well the skills you used as a host, merchant and sometimes bouncer in that place, and hope, when the killing it done, to have enough gold left to start up another inn.
Cellinthite Guide: The Holy Guides, Warrior Priests of Cellinthar'Valladir accepted you, and you serve with them. You are part chaplain, part warrior, you soul and life dedicated to protecting the vulnerable and weak against those that would harm them – all in the name of your noble and loving God.
Irinite Watch: You once served with the Watch of Irin (this could offer a range of bonuses depending on when you were in the watch. If it was when the fungi hit during the Sundering, your skills would be very different from those you would develop during a less exciting time).
Pentas Demonica Expat: Once you lived in the madness and horror of the City of Stained Stones. Now, for your own reasons, you have left, and although you have turned your back on that vile place, it, and those things within it, have left their mark...and indeed, may not yet be done with you...
As you can see, the backgrounds not only serve to shape what you will be good and bad at (they can, for example, inflict penalties in some cases – the Xix Touched may struggle with a Charisma check made to resist a madness inducing effect, suffering a penalty equal to the points they have invested), but when used with the “One Unique Thing” rule (another one I intend to use), can really flesh out your character, their past, and their future.