I like those ideas Nedylene, very good thoughts indeed. Harroghty is right on with the thoughts that fighters needs to be the ones that bring the big two items to the group: taking and dishing out melee damage. Notice the focus on melee damage, not magical because mages are always going to be the top dogs of dealing overall damage. The question really needs to get down to how we do it. We have two ideas that we have been kicking around so far:
Overall boost - this applies to the AC increase that has been discussed. That can be approached various ways, plate AC boost, fighter class specific AC increase when wearing heavy armor (because they eat, live, and sometime bathe in it), etc.
Additional Feats or Skills - like the stuff Nedylene was talking about. This could be a great way to approach it for a couple of reasons. Vibius posted about making them more valuable to a party, well the ideas for the Guard and Improved Guard pointed out gives them that.
Harroghty brought up a good point about why do fighters give up the skills of the ranger/paladin when you can't really tell the difference between the three classes? Well, here is how you answer that. Fighter class specific feats like the ones Nedylene suggested and fighter specific AC bonuses in heavy armor. You could even make it legit with the reasoning that Fighters dedicate themselves to combat, whereas Paladins have their focus split on fighting and faith as well as wondering where they will find their next princess to rescue, and Rangers have their focus split on fighting and nature as well as tree hugging and rescuing trapped felines from the evil grasp of tall tree limbs (drat..almost went a whole post without poking fun at my ranger buddies..oh well).
Or, we could do the only civil thing when two great choices are presented to us. Implement both, of course.

Good ideas everyone!