The following links are a good source of ideas for new projects.

www.allaboutcircuits.com : Web page with thousands of resources about electronic circuits, datasheets, projects, news, tools, among others
www.epanorama.net : Web page with electronic circuits clustered by topics
www.ee.washington.edu/circuit_archive/circuits : Web pages with electronic circuits for Audio, PC, Radio, and other related projects
www.nteinc.com : From this page you can download the Quickcross software. It allows to search electronic components like the ECG book. It also allows to download the datasheet for the selected device
www.cadsoftusa.com/download-eagle : From this page it is allowed to download the free program Eagle. It allows the creation of printed cirucits. Since this is a shareware program, there is a restriction in the size of the board, but in the others aspects, it is totally functional. It is also possible to download the program tutorial
www.electronicworkbench.com: From this page you can donwload a demo version of the Multisim or WorkBench programs. These programs allows the design and testing of electronic circuits, and the creation of a printed circuits. There are some restrictions with the demo version, such as it does not allow to save or to use some functions
https://electronicspoint.com: Web with many kind of Electronic resources, forums, tutorials, store, etc. that you can use for exploring the incredible work of electronics.