Operating systems: Windows, Linux, non-PC
Processor: asm x86, x51, Atmel AVR, Z80, mcc68k
Languages: c(15y), c++(10y), c#(7y), .NET, PHP, JavaScript, HTML, DHTML, CSS, XML
Database: SQLite, MySQL, SQL Server, Access
Communications: I2C, Wiegand, Manchester, RS232, RS485, TCP/IP, etc.
Can you be more concrete?