From all the printed circuit board (PCB) editor tools around, Eagle  seems a good alternative. The Freeware version is limited to a single working sheet, with a PCB maximum size set to 100 x 80 mm, double sided. This is perfectly usuable for small prototypes. Various licensed editions are available for larger projects. PCB can be manufactured by BatchPCB  or DorkbotPDX .
The default Eagle component library is growing every day and up to date components are available from CadSoft  web site. However, not all components are available and required to be edited from scratch. Some components are available for download from this section. Here you will find Informative Eagle tutorials from Hackaday [PART1, PART2].
An alternative to Eagle is the free PCB Artist software from Advanced Circuits  which is only available for Windows.
For circuit design and simulation, Texas Instrument provides a simple tool ( TINA-TI ). Free for download and easy to use it runs smoothly on Linux Host using wine.