In computing, Real-Time means the study of systems that must operate within strict time constraints. This is a very large class of systems, and it tends to include most applications with a user interface. For instance, if you go to Youtube and view a video, then this is a real-time application: the downloading, decompression and display of the pictures must happen at a strict schedule so that the movements are smooth and kept in synch with the audio.
From your expressed concern about power consumption, I surmise that you do not really mean "real-time"; rather, you want to know about embedded systems, another very large class of systems. Power consumption is most relevant for systems that must operate over a battery, so in particular portable devices.
The list of devices that use encryption is open-ended, so you cannot gather them all. However, one can remark that any system that engages in SSL/TLS will use one of the encryption systems that are supported in that protocol; this will most of the time be AES, 3DES or RC4. Among systems that do not use one of these three algorithms, the most notable are GSM phones; older protocol versions (2G) used A5/1, a custom stream cipher; newer versions (3G/UMTS) rely on KASUMI. An important point for the discussion at hand is that while A5/1 was designed for very low power consumption and easy hardware implementation, KASUMI is much more "software-like" in design, which means that for phones that support 3G, the encryption system has become quite negligible in the overall power consumption. Indeed, any smartphone will routinely engage in Web traffic, and this includes HTTPS, hence SSL, hence AES/3DES/RC4.
In any case, power consumption depends a lot on the implementation technology, so there cannot be any absolute answer; moreover, any comparison becomes obsolete after a few years, as technology evolves.
This article describes a comparison of various "lightweight" block ciphers, focusing on energy consumption in dedicated hardware platforms (i.e. custom ASIC). This should give you pointers, and accepted terminology for further Google-based searches.