Whenever someone says "my Aunt", "my Uncle" or "my cousin" in English, it's always felt very vague to me what the relation is. To describe it any further requires expanding it out into the base components of the immediate family which gets very clumsy.
In Chinese, the family title carries much more information with it, which side the relative is on, birth order, etc.
Wai-Yin Kwan's Chart is the most comprehensive list of family titles I could find. I had a quick glance through and I thought I saw an error or two, but I'll look at it a little more carefully later. I grabbed myself a copy and converted it to UTF-8 in case that site disappears.
It looks like Wai-Yin doesn't have the titles for "in-laws" beyond the spouse of the relative. At least for "Your Generation" and above, the spouse's family members in relation to the source person also have a whole set of different prefix characters as well. It also depends if the source person is male or female. And there are slight discrepancies between Cantonese and Mandarin; the terms for "mother-in-law", "maternal grandmother" and "paternal grandmother" can get really confusing between the two dialects. =)
There are also a few titles for polygamous marriages (well, really only polygynious marriages, though you could use the male forms for the equivalent polyandrous marriage). I say this because there are poly folks on my friends list who might be interested. =)
Speaking of family titles, this has been on my mind for a while.
Contrary to what certain unknowledgeable tattoo snarkers will tell you, 婿 actually does mean "husband". It describes a very specific type of husband: a daughter's husband. It is almost always used in conjunction with 女 in the phrase 女婿. The only time that I could imagine it isn't is in poetry when metre and compactness are needed.
It's only within that last 100 years that it's come to be associated more with "son-in-law". I think it might have still been used as "husband" in the late Qing dynasty and early into the new regimes.
I know that this was definitely the case with 媳婦, which used to mean "wife" and not "daughter-in-law". My impression is that it referred to a young, newly married first wife. "Daughter-in-law" used to be 兒媳婦, "son's wife". But 媳婦, on its own, now means "daughter-in-law".
This is in Chinese. I can't say how the denotation is different in Japanese.