I love Basecamp as a company, but it doesn't work as a generic note taking application.

I want to open my note taking solution, preferably with a shortcut and be able to jot down my thoughts right there. Plain text is fine, but markdown is preferred.

After I'm done writing, I can spend 10 seconds adding a tag or two so I can find it again using smart filters or searches.

I use basecamp - but how do you do wiki, notes type of things in basecamp ?

I keep a vim open all the time and quickly note it down. End of the day, I transfer it to Basecamp for future tracking or convert that to action items and schedule it