Legacy Family Tree has just added Maine to its offering of QuickGuides. These are very handy four page reference guides for genealogy research in each state, with online resource links, historical timelines, research tips, and migration routes. The Maine guide was created by New England genealogist and blogger Heather Rojo.
The PDF version of the Maine QuickGuide is only $2.95. You can also order a printed, laminated version. I ordered the PDF version and received my email with the download link within an hour. It's an excellent reference, and having it as a PDF allows me to view it on my laptop, tablet, or phone.
New Hampshire and Connecticut QuickGuides are available, as well as New Brunswick, Quebec, and Nova Scotia, with more New England states hopefully coming soon.
(Note: I have no affiliation with this product or Legacy Family Tree, and offer this simply as an informational resource.)