Thanks for the prompt reply. As I was learning to make my breadboard prototypes into PCBs I found this eagle schematic online (see C7 and C9 in the attachment). I've used it to build a few PCBs without problems but these capacitors always intrigued me.
I've seen this also in guitar pedal schematics where (as MAS3) mentions they were dealing with audio signals and it makes sense that they would want to block DC. Still it puzzles me , if what you say is true, how they were working in the attached schematics. In all the PCBs I made with this -not many- the VCC pin had 5V even with the "DC blocking" caps. But again, I might be measuring things wrong since I'm pretty new at this.
