I think, basic capacitor coupling is good enough for most applications under 100MHz if the source impedance is low enough. If it's high, use solution suggested by NANDBlog.
There's a place for topology complication. If use buffer, I'd add a cap to Vref/2 divider, so it works as a Lo-Pass filter and don't pick up garbage. If impedance matching is in demant there's another reason for topology to be evolved.
Comparing the two suggested schemes, DC-cap add some loss, ADC input currents may cause errors on the divider resistors, if you need to work with low frequencies, a cap may be just to big, etc) Op-amp solution is free of these disadvantages, but it's basically more pricey and takes more room on pcb and in the power budget as well.
There's a lot of subtleties, and I don't even know do you need them. :-)
And if you need to decoule the AC signal from the signal which contains both DC and AC, then there's not much of a choice but using decoupling cap anyway. Of course, there is (or I better say must be) some other clever ways, but I myself didn't give them much of a thought.
Sorry for the rant style) Dont really have time to edit and compile all this.