Codeplay Software offer a free "Community Edition" of ComputeCpp, their SYCL v1.2.1 conformant implementation and the developer website includes guides and documentation for SYCL developers.
There is a good set of SYCL sample code published on GitHub and this repository also contains some more substantial SYCL demo projects for N-Body simulation, Game Of Life and Mandelbrot.
If you'd like to watch a SYCL talk, there are some great talks online including Gordon Brown at CppCon 2018 "A Modern C++ Programming Model for GPUs using Khronos SYCL"
You can find more SYCL related presentation videos at sycl.tech
There are a growing number of Frameworks that are accelerated using SYCL. Some of these are listed on the Codeplay developer website and they include:
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