Although it's pretty easy to write, is there a chance you guys are going to support 〆 (pronounced しめ) in the future?
It's used to replace various kanji-kana pairs pronounced as しめ, like 閉め、占め、締め、and 絞め. The most common usage is in replacing the 締め in 締(め)切(り) to make it 〆切.
It's technically a kanji! Although a 国字 (kokuji, Japanese-made kanji) like 込,畑, or 働. It's got two strokes and is techinically under the 4th radical, 丿部.
Here's the links where I got the information (both in Japanese):
http://ja.wikipedia.org/wiki/%E3%80%86
http://kakijun.main.jp/page/shime02200.html