How do I keep the new line/line break/end of line in a file consistent across mac and windows
Which editors and viewers do you use?

This topic describes how to set newline in BBedit and Textmate. Also you can use TextWrangler and Notepad++ which are freeware

PS: I commonly use Vim in Windows and Mac (MacVim). In this editor I do ":set fileformat=dos" to convert to CR-LF