I visit the following sites, which are about how to be more
persuasive:

http://www.kevinhogan.com/
http://www.maxpersuasion.com/
http://www.mrfire.com/

I also read 'Influence' by Robert Cialdini and just ordered a copy of
'Power of Persuasion' by Kevin Hogan from www.amazon.com.

In the meantime, what other quality resources are there (online and
offline) that deal with how to be more persuasive?

Any personal recommendations would also be most welcome.

Hi!! Thanks again for another question.

The following are articles about improving one’s persuasion skills.

Online:

“Persuasion Analysis”
http://www.govst.edu/users/ghrank/ 

Egopower
http://sales-tips.industrialego.com/persuasion-sales-tips/ 

“Steve's Primer of Practical Persuasion and Influence”
http://www.as.wvu.edu/~sbb/comm221/primer.htm 

“Ten Persuasion Tips”
http://www.christianstudycenter.com/biblestudies/PF/11-10-02.htm

“Power of persuasion at the tip of your tongue”
http://baltimore.bizjournals.com/baltimore/stories/2003/03/31/focus3.html

“Top 7 Ways To Successful Persuasion”
http://top7business.com/archives/sales/20001115.html 

“Arguments and Persuasion Techniques in Writing”
http://www.csudh.edu/dearhabermas/argpers.htm 

“MAJOR PERSUASION TECHNIQUES”
http://www.e-onlinepublishing.com/chemistry/majorpt.pdf 

“Delivering a Persuasive Speech”
http://www.lessontutor.com/dppersuasive.html 

“Marketing Articles on Persuasion”
http://www.actionplan.com/artpers.html 

“Techniques of Persuasion”
http://www.uen.org/lessonplan/upload/713-2-1879-preve133.pdf 

---------------------
Offline:

“Persuasive Business Proposals”
http://www.psgcompany.com/tips.html

“Artful Persuasion: How to Command Attention, Change Minds, and
Influence People”
http://www.amazon.com/exec/obidos/tg/detail/-/0814470637/002-7635134-6878428?vi=glance

“Influence (rev) : The Psychology of Persuasion”
http://www.amazon.com/exec/obidos/tg/detail/-/0688128165/ref=pd_sim_books_2/002-7635134-6878428?v=glance&s=books

“Get Anyone to Do Anything: Never Feel Powerless Again--With
Psychological Secrets to Control and Influence Every Situation”
http://www.amazon.com/exec/obidos/tg/detail/-/0312270178/ref=pd_sim_books_2/002-7635134-6878428?v=glance&s=books

“Words That Change Minds: Mastering the Language of Influence”
http://www.amazon.com/exec/obidos/tg/detail/-/0787234796/ref=pd_sim_books_4/002-7635134-6878428?v=glance&s=books

“So you'd like to ... Master Persuasion techniques” (A set of
recommended books on persuasion skills)
http://www.amazon.com/exec/obidos/tg/guides/guide-display/-/790VANW2SOOU/ref%3Dcm%5Fbg%5Flm/002-7635134-6878428

“Essential Skills” (Seminar)
http://www.essential-skills.com/?r=gAW 

“Conversational Jujitsu” (seminar)
http://conversational-jujitsu.com/ 

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I hope these links would help you in your research. Before rating this
answer, please ask for a clarification if you have a question or if
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Regards,               
Easterangel-ga               
Google Answers Researcher

In addition to the books on easterangel's excellent list, I have one
additional suggestion:

"How to Get People to Do Things," by Robert Conklin.

http://www.amazon.com/exec/obidos/tg/detail/-/0345327306/002-2704227-8630461?vi=glance

Despite the trite title, this is a very insightful book.