Coherent light scattering by a disordered medium produces a speckle pattern whose statistical properties have been extensively studied. On the fundamental side, intensity fluctuations and correlations are basic ingredients in mesoscopic phenomena. On the applied side, they offer the possibility to design sensitive sensing and imaging techniques to probe complex media. We will discuss situations in which unexpected behaviors show up, such as speckles fluctuations produced by fluorescent sources immersed inside the scattering medium, or cross-correlations between speckles reflected and transmitted by opaque strongly scattering media.