Reposted from my personal blog: I just wanted to post quickly, about 4, really 2, feats from the 3E core selection, that I feel are really under-rated.

Weapon Focus [General]
Choose one type of weapon. You can also choose unarmed strike or grapple (or ray, if you are a spellcaster) as your weapon for purposes of this feat.
Prerequisites: Proficiency with selected weapon, base attack bonus +1.
Benefit: You gain a +1 bonus on all attack rolls you make using the selected weapon.
Special:You can gain this feat multiple times. Its effects do not stack. Each time you take the feat, it applies to a new type of weapon.

What I really want to talk about here is Weapon Focus - Dagger. See, a dagger is concealable, light for making off-hand attacks, common, and everyone can use it (okay, sorry, not Monks). It is also a great tool, for carving things, breaking locks quieter than a sword stroke, and good for eating with. Plus it can be thrown. There are very few weapons that can be thrown and wielded in melee, and the dagger is probably the best of these. Why is this important? Well, Wpnfcs anything else is usually a melee or a ranged thing. But by taking it for the dagger, you get to use both - twice as much featage for your money. A great feat for a great weapon, both overlooked in favor of larger weapons.

Iron Will [General] (Also the Reflex and Fortitude versions of this feat)
Benefit: You get a +2 bonus on all Will saving throws.

I love the saving throw feats - Lightning Reflexes was the first feat in 3rd edition that I ever took! These feats are great for a couple of reasons. First off, you will make saving throws all the time. So in terms of investment, attack-roll (for fighters) feats are probably the only feats that you're going to get more overall uses out of. Since the core saves work on a 1-12 scale, a +2 bonus is worth a 1/6 of your total increase. Or to look at it another way, as the rolls are done on a d20, it's a free +10% bonus to everything you roll. That soon adds up over the course of a campaign - real value for money. Since this bonus is considerable, the feats really let you both #1 specialize, becoming a monster when it comes to your chosen save, and #2 shore up your character's shortcomings. As mentioned above, Lightning Reflexes was the first feat I ever took, for my cleric. With a 13 in dexterity, poor save progression, and wearing heavy armor, I was afraid of falling at the first reflex-trap we encountered. However the feat let me even my odds out a bit and saved my butt on several occasions.

There you go, two/four of my favorite feats and the reasons why.