list of mantras and their meanings and benefits

[ken p]

http://www.mindbodygreen.com/0-8188/5-ancient-mantras-that-will-transform-your-life.html

http://indusladies.com/community/threads/mantras-and-their-benefits.83894/

http://www.insightstate.com/video/best-hindu-mantras-and-their-meanings/

http://isha.sadhguru.org/blog/yoga-meditation/demystifying-yoga/mantras-explained-mantra-to-transformation/

https://en.wikipedia.org/wiki/Mantra

http://www.sunnyray.org/Mantras-for-meditation.htm

One may add more mantras given by your spiritual  guru here. 

[Venkata Sriram]

Mantras initiated by one's guru should never be disclosed openly.  The mantra-chaitanya gets depleted.  the mantra shastra clearly says so.

Now-a-days, the so-called self-styled modern gurus initiate every tom, dick & harry indiscriminately without following shastra and sampradaya.

Currently, a self-styled swamiji (name withheld) is initiating his gullible disciples with chaNDi-navAkSari mUla mantra with online registrations and demanding guru dakshina thru

PAYTMs and credit cards.  He is also offering early bird discounts !

हत विधि !

[Ananthanarayanan Vaidyanathan]

it is also seen that people just publish mantrams with meaning and all especially across social media.. We fail to understand that mantras are not just letters or words in a language.. though they may have that sthoola form too...and initiation of any mahamantras other that through a guru is normally not expected.. 
Of course, I read in a text that even if we overhear a mantra at any time during our visit to the abode of Shiva, then we can consider ourselves as being initiated to that mantram..  But this statement appear to have been made to underline the greatness of Lord Shiva rather than as a rule for use of mantrams..
If one is eligible for a mantram, the proper time, the proper guru and proper settings would arrange themselves, it is believed.
But then it is one of the lakshanms of advance of Kali Age that we would be doing things which should never be done..