For low power applications, although its probably not ideal, I tend to use a max232 equivilent to get +/- 10V rails. Its pretty easy and means you can use opamps which can't go to either rail, using a 5v supply. There are also several charge pump IC's which can invert or double the voltage, much like the max232 except they have lower output imedences (+/- 25mA) and wuth an LDO, you can regulate these rails.
Only thing is, these converts have noise, sometimes in the audio range, which can bleed into your inputs/outputs. I did make a fairly decent 2W switch mode supply for low power that takes in anythigng from 3 to 9V, and kicks out +/- 12V using a coupled inductor (and a few transistors) - but thats hardly simple, and overkill for most situations.
If we're tlaking prototyping, might be an idea to invest in a dual output wall wart, with some regulation and filtering.