My opinion is that the ranger class is poorly conceived in 3E. It stacks too many of it's benefits at first level (making it the multi-classing munchkin's dream) and then gives out very few powers later on other than advancement of a modest spell list. The distributon of favored enemy bonuses is also pretty weak though kind DMs can continue to make early choices relevant thanks to the flexibility of 3E and monsters gaining levels.
As the class currently sits, there is a huge incentive for picking up 1 level as a ranger (for the 3 bonus feats). THere is also an incentive for picking a favored enemy that's useless to low levels so that it'll be suitably high when the PC is high enough in level to take the monsters on.
I can think of a couple of improvements that I don't think would seriously damage the ranger's balance. Give them 6 skill points per level. Hey, 4 is nice but it's still hard to maintain move silently, hide, search, spot, listen, animal empathy, and wilderness lore without a really high intelligence. They get more skill points than a fighter, but they really need to use them to differentiate themselves from the fighter.
Give them a bonus fighter feat every 5 levels. It won't be much (fighters get them every 2 levels) but it will help.
Change the way they get favored enemy bonuses. The ultimate total of their bonuses is +20. Currently, at 1st level they get 1 point (+1 vs enemy A). At 5th level they gain net 2 (+2 vs enemy A, +1 vs enemy B, for a net change of 2 points in bonuses) . At 10th level, they gain 3, at 15th they gain 4, and at 20th they gain 5. We can spread that out a bit and give them more choices so that their original enemy isn't necessarily the one with the highest bonus at the end (which could reflect a major change in priorities for the ranger character as to which enemy is most dangerous).
So, give them a +1 each level, must pick 1 new enemy every 3 levels until they have reached a max of 5 (at 12th level), no enemy's bonus may be greater than +5.
Well, that last one is just an idea and is a little more complicated. But I really think the ranger is out of whack compared to other classes in the long run.