Have you looked at Szatany's Ultimate Ranger class at the WotC messageboards? Definitely check it out.
My favorite replacement ability is....
Safe Passage: When traveling overland in natural settings, the ranger and the group he/she guides may get along more easily when moving overland. The group may perform one of the following actions without affecting their overland movement rate. Normally these actions all require that the group reduce their movement.
• Travel at normal rate while foraging and hunting. (See the Survival skill)
• Travel at normal rate while hiding the group’s tracks. (See the Tracking feat)
• Travel at normal rate while protecting themselves from dangerous weather. (Survival skill)
• Travel at normal rate in darkness or fog. (See the Adventuring Chapter)
• Travel at normal rate while avoiding encounters and remaining unseen.
I like the idea of having different abilities based on different ranger archetypes. For example, a "Scout" archetype might have the lookout ability....
Lookout: The maximum distance for spotting the presence of creatures is increased by 50% for the Scout (e.g. when in the desert, instead of (6d6x20) 360 feet, the Scout would detect creatures at up to 540 feet). Also, when spending a minute scanning the area in his/her field of vision, the Scout can maximize the base die roll to determine maximum spotting distance (e.g. 720 feet in the desert).
Archetypes that fit the ranger include: Bandit, Bounty Hunter, Guide, Nomad, Scout, and Wanderer. Perhaps as a ranger gained in levels, he would get an extra ability associated with the archetype he was currently pursuing.
For example: Bandit I (demand toll), Bandit II (ambush), Bandit III (band of merry men)