Does anybody know of a twitter/RSS/blog etc. that has a quote-of-the-day in Japanese?

No, but a friend posted this on Facebook today:
人間生まれてきた時は裸。
死ぬ時にパンツひとつはいてたら
それだけで勝ちやないか。

There's a ton of them. Just Google 今日の名言. Most have a lot of translated from English/other language quotes though, so you might not want to put them in anki, e.g. this one's currently from Plato: http://www.iwanami.co.jp/meigen/

it wouldn't be one a day (more frequent) but search like 名言bot or 格言bot etc and you'll get lots of twitters.