Thanks to Matt‘s link earlier this week, several new people found How to Japanese, including Akaki who knows a thing or two about 変換! He provided a bunch in the comments. I’ll repost them here.

“音符（おんぷ）＝♩
Also 郵便（ゆうびん）＝〠 (look at the guy!)
あっぷる＝（in kotoeri）
ルート＝√
平方メートル（へいほうめーとる）＝㎡
平方センチメートル＝㎠ (note how the exponent is actually part of that single character)
メートル＝㍍
ワット＝㍗
キロメートル＝㎞、㌖
etc. units.
明治（めいじ）＝㍾
大正（たいしょう）＝㍽
昭和（しょうわ）＝㍼
平成（へいせい）＝㍻”

“Oh and あっぷるぱい＝π :)”

I love the fact that all the units can be compressed into a single character-space – clearly useful. I wonder about the era names, though – you’re only saving one space! Cool to see that Apple got into the action by creating a kotoeri-only 変換.

My previous posts about 変換 are here, here and here. ♨ is still my favorite.