The FanCC system is one that I always liked. Unfortunately, I can't find the Netbook of Spells anymore, but this is from the Netbook of Feats. It should be a good starting point (in many cases, change "feat" for "spell").
Feat Ratings
Purpose: Here are questions we ask when evaluating a feats purpose. Would anyone want to take this feat? Have I seen something like this in a movie or book? Does the feat help me to make a certain kind of character? Are there already feats that accomplish this goal better than this one? Is this feat just a weaker version of some spell or class ability?
5 – This is a feat that makes a character more exciting and interesting.
4 – This is a feat a lot of players and GMs would like to use.
3 – While not exciting, this feat will appeal to some players.
2 – Its hard to imagine anyone who would want to take this feat.
1 – This feat is almost completely useless no one would ever use it.
Power: This is perhaps one of the most important ratings. When rating the power of a feat we usually compare it to the feats in the SRD with similar prerequisites. We rate feats lower for being too strong and for being too weak. Every feat should give the character some kind of useful advantage, but shouldn’t give the character more of advantage than a character level or a spell. We try to think of ways to combine the feat with others, and ways it could be abused or taken advantage of.
Feats vary a lot in overall power, but high prerequisites will help a powerful feat’s rating in this category.
5 – This feat is useful, well balanced for its prerequisites, and almost impossible to abuse.
4 – This feat may be a little strong or a fairly weak, but its within the norm of the SRD.
3 – This feat is either very strong or almost uselessly weak. It might not unbalance a game but if taken full advantage of it might.
2 – This feat is simply too strong for most peoples campaigns, it will unbalance the character that takes it.
1 – This feat is ridiculously strong and is probably better than a full character level.
Portability: This is a measure of how generally acceptable a feat is from one campaign world to another. It takes into account cultural assumptions, power level, use of special rules, and the like. Some feats may suffer because they seem implausible to perform, while others will suffer because they are specific to an unusual race or culture.
Sometimes a feat with a low power rating will suffer here because its unlikely many DMs will accept it without special circumstances.
5 – This feat could be used in nearly any game or campaign setting.
4 – This feat may not fit in to some games but is generally acceptable.
3 – This feat has some very specific requirements or assumptions about the game world.
2 – This feat is probably only useful in a specific and unusual campaign world.
1 – This feat is very exotic or for some reason wholly unacceptable to nearly anyone but its author.
Complexity: This is one of the easier categories to judge.
Here are some questions we ask when evaluating complexity. How easy is it to understand the feat? How long is it, and how many different rules does it have?
Would the feat make combat or other situations more time consuming and monotonous? Could this feat do the same thing but in a more simple fashion? Does the feat require bookkeeping? Does the feat clearly explain how it is used, or are there a lot of unanswered questions?
5 – Simple as pie. The effect is clear and concise; it may even eliminate complexities in the standard rules.
4 – An average feat, it is probably well written but simply involves more rules than a 5.
3 – Either a very complicated feat, or one that needs to be tightened up.
2 – Almost hopelessly confusing or involved.
1 – A real mess, its just too much information for a feat or is nearly impossible to understand.
Rules: This covers two major concepts. Firstly does the feat follow the SRD rules properly and does it explain its mechanics properly. Second does the feat follow the standard feat guidelines and conventions. This category is where the expertise of our staff comes into play.
5 – This is a prime example of what a feat should be.
4 – This feat breaks some convention or standard of feat design bit its not serious.
3 – This feat is definitely outside the scope of a standard feat, but it is still playable.
2 – This feat does not follow the SRD rules well or is very much not what a feat should be.
1 – This isn’t really a feat at all or completely misinterprets the SRD rules.
Overall Rating: This is the average of the five categories, and represents the overall quality of the feat. Any feat with an overall rating less than 3.0 is simply not included in the Netbook. Many feats get a low rating when we first review them, but by the time we are finished working with the author nearly all feats achieve a 3.0 or better or are withdrawn by its creator.
4.5 to 5 - This is the pinnacle of featsmanship, a real gem.
4 to 4.5 - This is a good solid feat and should be acceptable for most games.
3.5 to 4 - This is a decent feat but it has some features that might make it unacceptable.
3 to 3.5 - This feat is not for everyone but still has value for the right game.
Andargor
