My house rules for languages (and thus I get this thread moved to House Rules):
The Speak Language skill doesn't work like other skills. It works as follows.
• Speak Language is a class skill for everyone.
• You start at first level knowing one language based on your culture, gaining three ranks automatically. Additionally, in my campaign, you receive 6 + Intelligence bonus bonus skill points at 1st level, which you may apply to languages, craft, or profession skills.
• Each time you purchase a rank in Speak Language, you must choose a language that it applies to. There is almost no reason to need a language skill to go above 4 ranks, since 4 ranks equals perfect fluency and knowledge of linguistics. Additional ranks are useless.
• Most languages belong to a language group. Whenever you try to express yourself in a language you have no ranks in, but you have ranks in another language in that language group, you can communicate as if you had 2 ranks lower than the related language you know.
• If you have the Literate feat, you can read languages that you can speak. Most cultures gain the Literate feat automatically. Some primitive cultures might give characters a different bonus feat.
• Whenever you wish to use any Charisma-based skill in a method that involves language, you suffer a -5 penalty for each rank you have less than 3 in the language you are speaking in. A foreigner could easily intimidate someone by looking mean and dangerous, or bluff someone into blocking left as he attacks right, but he'd have to rely just on simple gestures and force of personality to try to lie to someone, entertain them, or negotiate with them. This penalty also applies to Perform check for the bardic music abilities Fascinate and Suggestion.
Language proficiency comes in four ranks.
• 0: The language is practically unknown to you, and at best you know a handful of stock expressions.
• 1: You know the basics of the language, and can express and understand simple concepts.
• 2: You can express and understand everyday concepts, but have trouble with complicated speech. You can understand speech as long as the topic remains fairly constant, but you have trouble following conversations when the subject changes.
• 3: You are as fluent as any normal person who speaks that language, though you may have an accent.
• 4: You understand the language with the knowledge of a scholar, and can freely use different accents as you desire. This rank is the equivalent of a highly technical, poetic, idiomatic, or slang-riddled piece of language, such that even normal native speakers may need one or two tries to figure out what's being said.
The following rules are only for if I want to get complicated. Normally I'll just gloss over what's being said.
Expressing Yourself
Whenever you want to express yourself to another person in a language, if both you and the person you are speaking to have enough fluency in the language that you both understand, there is no need to make a Speak Language check. If you are not fluent enough, make a Charisma check (DC 0 +5 for each level you lack in knowledge).
Example One: An adventurer with only 1 rank in Elvish tries to explain to an Elf that he is an adventurer and that he is in trouble. He does not need to make a check, since this is fairly simple. However, he also wants to explain that an invading army is approaching from the south, with a few thousand warriors. This is a complicated expression (needs 3 ranks), so must succeed a DC 10 check. If he then wants to explain that the general is actually collaborating with an Elvish noble in this land, he would need to make a DC 15 check. Then, later, if he tried to convince the Elvish noble to stop aiding the invading army, our adventurer would suffer a -10 penalty to his Diplomacy check.
Understanding a Language
If you are trying to understand someone speaking to you in a foreign language, make a Sense Motive check (DC 10 + 5 for each rank lacked, by both you and by the speaker).
If you are trying to read a language, make a Decipher Script check (DC 15 +5 for each rank you lack to understand the expression).
Spells and Translation
The Comprehend Languages spell grants you 1 rank in one chosen language, but no longer has the touch range requirement. Tongues grants you 2 ranks in all languages. Greater Tongues (6th level spell) grants you 4 ranks in all languages.
Failure
If you fail an attempt to express yourself or to understand someone else by 4 or less, you may still get close the mark, the equivalent of a very simplified version of what you meant to say. Failing by 5 or more means the speaker can't understand you at all. Failing with a natural 1 means the speaker misinterprets what you say to mean something drastically different.
And a good point. Sigh. 
