[KyleGoetz]

Some, including myself, were confused about 間 and 間に issues. Masaegu gave some terrific help. I also did a little reading on my own, and, combining that with what Masaegu had said, I thought I'd put something in a thread by itself.

間 versus 間に
From what I have been able to glean, there is a pretty important distinction between these two constructions. When you use X間Y, Y happened the entire time X happened. When you use X間にY, Y happened at some point during the time X happened.

I have a number of sample sentences taken from textbooks and such. Note that in the first set, Y happens the entire time X happens, while in the second set, Y happens at some short period of time within the duration of X:

【間】
ルームメイトがコンピューターを使っている間、私は本 を読んで待ちました。
While my roommate used the computer, I read a book, waiting.
彼が出かけている間、私はずっと手紙を書いていた。
While he was out, I wrote a letter the whole time.
母が料理を作っている間、子どもはテレビを見ていまし た。
While the mother cooked dinner, the child watched TV.
彼女が着替えている間、僕は外で待っていました。
While my girlfriend changed clothes, I waited outside.
大学に通っている間、ずっと京都に住んでいた。
While I went to university, I lived the whole time in Kyoto.

【間に】
お風呂に入っている間に、電話がありました。
While I was in the tub, the phone rang.
ゆうべ、寝ている間に、地震がありました。
At night, while I was sleeping, there was an earthquake.
電車に乗っている間に、友達からメールの返事が来た。
While I was riding the train, the reply email from my friend came.
私は日本にいる間に、結婚しました。
While in Japan, I got married.
子供が寝ている間に、洗濯をした。
While my child was sleeping, I did the laundry. [note: the implication here is that for some subset of the time the child was sleeping, the speaker did the laundry; it didn't take her the entire naptime to do it; had this been 間 instead, the implication would be that it took the entire naptime, and (I guess) the laundry person may not have even finished all the laundry, but doing the laundry occupied the entire naptime]

Negative modifiers
You can have ない間（に） just like you can have affirmatives like those above. Here's an example:
私がいない間にだれか来たのでしょうか。門が少し開い ています。
While I was not here, someone came[, didn't he?] The gate is slightly open.

Past tense modifiers
To be continued. I'm still doing reading on this and learning.