Extracellular multi-electrode recordings allow to isolate spiking activity but also yield the slower and often periodic local field potentials (LFP) that reflect a superposition of spiking, synaptic and subthreshold activity. While impulse-like waveforms (spikes) and periodic waves (oscillatory LFP) coexist in such recordings, most current efforts in data acquisition, analysis and modeling focus on the spiking activity. Although correlations of oscillatory activity with brain function and behavior have been shown empirically, the computations enabled by brain waves and their interaction with spikes are still unclear. My talk will describe two recent forays in this direction. The first part describes a method how to quantify the amount of information a spike train carries about an oscillatory intrinsic brain signal observed simultaneously. The second part of the talk describes the recent finding that oscillatory LFPs carry exclusively detailed behavioral information. In the hippocampus of a navigating rat, place neurons discharge selectively when the rat is at certain locations. In contrast, the LFPs during navigation exhibit a powerful traveling wave at 9Hz propagating through the hippocampus and exhibit very little place-tuning at single anatomical sites. It was believed that the 9Hz wave represents the animals behavioral state but by itself contains little specific information about the animals behavior. We could recently demonstrate quite the contrary: the LFP structure at multiple sides contains detailed information about the place of the animal. Specifically, the location of the animal can be decoded from the LFP with comparable precision as from the spike trains detected in the same recordings.