I don't want a fully fledged Eclipse project or depend on heavy Eclipse for anything.~
I don't know if you have the same feeling, but it doesn't look like a good idea to depend on one heavy tool for anything in your electronic project. Having easy-to-understand scripts for building or debugging the project will make the life easier to newcomers (...or to yourself when you come back 3 years later and all the tools you used initially are now outdated).
Of course, from a former continuous integration engineer, I would also rise the obvious problem of automating your project in a CI environment. Yes, Eclipse can run headless, but this this is a dirty solution. Simple command-line tools are the way to go.
But, you still want a modern IDE where you can program and debug in the same tool. Proprietary debuggers such as Greenhills MULTI, Lauterbach Trace32, iSystem WinIdea, PLS UDE... are very well integrated for debugging, but not very much for programming. Also they are very expensive. Still have a look at iSystem WinIdea Open, which is free for ARM development and comes with a nice DIY hardware debugger board (see the do-it-yourself iTAG.ZERO and the 50€ iTAG.FIFTY at ). Unfortunately this last option only works with Microsoft Windows.
By the way, I discovered there is a standalone eclipse debugger .
I like Greenhills MULTI and it works under GNU/Linux as well, but there is no free/non-commercial version.
For the hardware debugger probe, don't forget to check the famous and always well-supported SEGGER J-Link. Also see the "Why J-Link?" section of GNU ARM Eclipse project at  for explanations about the advantages of this probe (e.g., 15MHz JTAG). The education/non-commercial version named "SEGGER J-Link EDU" costs about 60€ (without VAT), see at Farnel .
There are Chinese copies of the J-Link easily found on eBay or Taobao for about 10€, but be careful that SEGGER invests a lot of efforts into fighting illegal Chinese copies. The official J-Link software  will brick your Chinese J-Link probe by flashing a new (brocken) firmware automatically.
The ST-Link/OpenOCD way
If you stick with ST microcontrollers, the ST-Link is cheap and well supported by open source tools. The ST-Link is embedded on ST discovery boards, which are so cheap that you can afford a board only for the debugger part. The STM32F0 discovery board comes with a ST-Link/v2 for less than 10$. The ST-Link can be used to debug another ST microcontroller using the SWD connector. A long discussion from Andy Brown about the advantage of the ST-Link can be found there .
By the way, there are also illegal Chinese copies of the ST-Link (this one does not look very much ST  for example), but I can't see the point of supporting Chinese illegal copies when the original is just a few € more.
According to a quick probe on the SWCLK (common with JTAG's TCK) clock signal, the adapter appears to run at 1.5MHz.
How to architecture your embedded project?
If you want an all-in-eclipse project, I suggest to follow the 4-part tutorial from Akhmad Hendriawan at , ,  and . The problem is, as explained a the beginning of this post, that everything depends on eclipse, which is bad (R)
In addition, I am targetting a bare-metal solution, excluding any compiler start-up and standard C or C++ library (newlib).
Create a new empty project:
By disabling the default build command, all the GNU ARM Ecplise auto build is removed: