Hi there,
I'm very often put in the position of writing thank-you notes for
various occasions (the most common ones obviously being gifts, events
I've been invited to, dinners, etc.) However, my note-writing skills
are pretty poor. I'm looking for (1) some general advice on writing
interesting, warm, enjoyable thank-you notes, and (2) (if possible) a
website/book/etc. with a relatively large list of stock letters that
could be adapted for my own use.

Thank you!

Hi gavinguy:

Thank you for your interesting question! ;-) 

And thank you for caring enough to want to learn about how to write an
effective thank-you note - what is quickly becoming a lost art.

There is a wealth of information on the Web about this subject, but
much of what is available is of a professional/business nature
(typically in response to an interview). I was able (with the use of
the "-" syntax in Google) to weed out much of this superfluous
information and find some great sites for you to visit.

Some of the best, simplest, general advice I found on writing
thank-you letters came from the University of Kentucky website.

Writing Letters
URL: http://www.ca.uky.edu/fcs/FACTSHTS/HF-LRA.102.PDF
Quote: 
"There are no set rules for writing thank-you notes to friends and
family. Here are some things to keep in mind as you write your
letters.
1. Write as you talk.
2. Do not make excuses for not having written sooner.
3. Express your thanks clearly and briefly.
4. Printed thank you cards are not necessary. A personal note on plain
paper is better than a printed thank-you note with just your
signature.
5. The wording of the closing phrase depends on the person to whom you
are writing. Some suggestions are 'Sincerely,' 'as ever,' and 'Love.'"

Other valuable information can be found at:

Sample Thank You Letters 
URL: http://www.bedrestsupport.com/Thankyous.html
Quote: 
"Keep in mind, a thank you letter doesn't need to be lengthy or overly
gracious. Be sincere in your approach; write the letter as if you were
the one receiving it. Other tips on writing thank you letters, as well
as a few samples, are below:
* Write your thank you notes within one to two weeks of receiving a
gift; for services, dinners, or hospitality, within a day or two. If
you are unable because of special circumstances, you may want to ask a
friend, your spouse/partner, or other family member to write a few for
you.
* Be specific when thanking someone. Highlight what pleased you most
about the gift, favor, kindness, service, etc. Even if the gift is not
something you needed or wanted, you can focus the attention of the
letter on the person who gave you the gift.
* Avoid the following when writing the letter: General remarks of
thanks ('thanks for the gift/service'); mentioning dollar amounts for
monetary gifts or certificates; mentioning receiving more than one of
the same gift; asking for the receipt so you can exchange it or get a
refund for it; saying 'thank you' over and over; using thank you
letters as a means to discuss news, information, questions or
comments; and, forgetting someone's name when the gift or service came
from a group of people."

The following site has some online examples of thank-you notes that
might prove helpful.

Thank You Letters
URL: http://www.weddingguide.co.uk/articles/planning/thankyouletters.asp
Note: These are wedding-related thank you letters, but can be used as
models for other occasions.

As well, the following books - containing writing tips and plentiful
examples - can be purchased online:

Writing Notes With a Personal Touch
http://www.amazon.com/exec/obidos/tg/detail/-/1567996620/qid=1038174262/sr=1-1/ref=sr_1_1/002-7806935-5796805?v=glance&s=books

The Thank You Book: Hundreds of Clever, Meaningful, and Purposeful
Ways to Say Thank You
http://www.amazon.com/exec/obidos/tg/detail/-/1563526514/ref=pd_sim_books_1/002-7806935-5796805?v=glance&s=books

When Words Matter Most: Thoughtful Words and Deeds to Express Just the
Right Thing at the Just the Right Time
http://www.amazon.com/exec/obidos/tg/detail/-/0517704064/ref=pd_sim_books_4/002-7806935-5796805?v=glance&s=books

However, if you are using these sample letters, please remember that
it is important to balance that with personal touches that express
yourself.

I hope this information is of help to you.             
            
If you need any clarification of the information I have provided,
please ask using the Clarification feature and provide me with
additional details as to what you are looking for. As well, please
allow me to provide you with  clarification(s) *before* you rate this
answer.
                        
Thank you.                         
                        
websearcher-ga                        
                        
                
Search Strategy (on Google):            

writing "thank you letters" personal -professional -interview
://www.google.com/search?hl=en&lr=&ie=ISO-8859-1&safe=off&q=writing+%22thank+you+letters%22+personal+-professional+-interview

Thanks websearcher, your reply is exactly what I was looking for.