Personal letters can be divided into two broad categories, based on the intended recipient: person-to-person letters and person-to-business letters.
It is important to note that a lot of confusion exists as to what are true personal letters and what are NOT personal letters. For example, a "cover letter" used to transmit a report is NOT a personal letter - it is a business letter. On the other hand, a "cover letter" for a resume or c.v. IS a personal letter.
Letters that some people loosely define as personal letters which are NOT personal letters at all include: covering letters, employee letters, introduction letters, marketing letters, publicity letters, project letters, customer relation letters, financial and credit letters, order-related letters, sales and marketing letters, follow-up letters, announcements, fundraising letters, among others.
The links below will take you to typical sample letter templates for the two primary categories of personal letters:
Person-to-Person Letters
"Person-to-person letters are letters that one individual sends to another individual that deal with personal matters, as opposed to business matters."
The following links go to real-life templates of the most commonly requested person-to-person letters:
Character reference letter - personal friend/colleague reference.
Church letter - to parents re: child's birthday.
Condolence letter - to an acquaintance or colleague-哀悼信.
Friendly letter - to a colleague and sports buddy-.
Goodbye letter - farewell letter to co-workers-同事再见信.
Love letter - to someone you've known for a while-情书.
Letter of apology - to a neighbor or acquaintance-道歉信.
Letter of complaint - water damage complaint to neighbor-投诉信.
Letter of congratulations - to a friend or colleague-祝贺信.
Letter of personal reference - recommending a personal friend-个人推荐信.
Letter of resignation - resign from a committee-辞职信.
Letter of sympathy - to family of a friend and/or colleague-慰问信.
Letter of thanks - to friends or acquaintances(熟人)感谢信.
Letter of welcome - to a new community member-欢迎信.
Romantic love letter - after a special evening.
Teacher letter to parents - beginning of year guidelines.
Thank you letter - personal thanks to a family member(感谢信).
http://writinghelp-central.com/sample-letters-personal.html