In many cases I'd like just to open a file, edit it quickly and check if it compiles. I do not care what compiler and what flags to use. I do not like to pay price of project creation to do this simple thing.
I'd suggest:
- to allow to compile *ANY* file open in the editor with default toolchain and some default flags, even if it does not belong to any project
- to allow to compile it to object file if there is no "main" in the file and to executable "a.out" if there is one (it is enough to have a default Makefile for this)
- to enable "Run" and "Debug" buttons in "Output" window for file that were compiled into a binary (Debug should work as step into main)

Look at this article to see large demand in this functionality:
http://www.sdtimes.com/content/article.aspx?ArticleID=34559&print=true