While I didn't want to do a lot with changing skills, I found that many skills were underutilized. In many cases, I had player characters wanting to do things that would require new skills unless I modified existing skills. Most notably, skills dealing with herbs and healing were lacking in information and ability so I have expanded skills to give players more control over what they need to do.
||The rules for the Heal skill didn't really cover mixing skills and was overly limited in the definitions of what players could do.
||Since a lot of player characters believe in Astrology, and the only other skill was Knowledge Planes (which covered too much), this skill developed as a useful alternative.
||Players needed something a little more about what they could do in the wilderness. We also had characters in our campaign who were basically "herb witches" that needed a way of quantifying their abilities.
||This skill was created for, and is used by the Ritual Magic used in the Traykon campaign.
||Other than Bardic Performances, there needed to be some expansion of the Perform skill. My primary campaign had a player character Rogue who used Perform nearly daily.
||Just as with the Knowledge: Nature skill, this skill works for those various "herb healers" and "hedge witches" that were common in the campaigns.