When you're a freelance editor -- specifically an editor who specializes in academic, scientific and academic articles/papers -- you'll do well to have several online resources handy, especially when you're out of your comfort zone (and text references are out of reach) and the deadline is hanging inches from your head.
Based on experience, I have always found the following web sites very helpful:
- Merriam-Webster Online Dictionary (for US-style projects)
- Oxford Dictionaries Online (for UK-style projects)
- NCBI Journals Database (for an extensive list of journals; the list is by no means complete, but if you're searching for information on medical, biological, and other scientific journals, this is the site to check out)
- CASSI Search Tools (Journal abbreviations)
- EMBASE Journals (you can download your own copy of the list of EMBASE journals here)
- Chicago [MoS] bibliographic style (for citation and formatting; there are other sites that you can use, but I find their tutorial and guidelines easier to follow)
- List of country codes (country codes, what else?)
- Franks Compulsive Guide to Postal Addresses (state abbreviations, country-specific information on postal addresses, etc. -- a very useful site, which should be on everyone's list)
On the practical side of things, make sure that you have the following sites bookmarked:
- World Clock (to keep up with the times)
- Paypal (a useful payment option)
- Currency & Exchange Site (money matters)
This is all I can think of for now. I shall be expanding this list from time to time because I am sure there are other helpful sites out there waiting to be sniffed out.