Guru: Om Gurave Namah

Lord Ganapati: To remove obstacles, Om Sri Ganapataye Namah

Lord Shiva: Good for all purpose, Om Namah Shivaya(Panchakshara)

Maha-Mrityunjaya Mantra:
Om tryambakam yajamahe sugandhim pushtivardhanam
uurvarukamiva bandhanaan mrityor mukshiya maamritaat.

Sri Devi:Om Sri Durgayai Namah

Sri Kalika:Om Sri Kalikayai Namah

Sri Lakshmi:Om Maha-Lakshmyai Namah

Lord Hari: Om Namo Narayanaya
Hari Om
Hari Om Tat Sat

Maha-Mantra :
Hare Rama Hare Rama Rama Rama Hare Hare
Hare Krishna Hare Krishna Krishna Krishna Hare Hare

Om Namo Bhagavate Vasudevaya

For delay in marriage: Om Sri Krishnaya Govindaya Gopijana Vallabhaya Namah

Om Sri Krishnaya Namah

Sri Hanuman: Om Sri Hanumate Namah

Lord Rama: Om Sri Ram Jaya Ram Jaya Jaya Ram
Om Sri Ramaya Namah
Om Sri Sita-Ramachandradhyam Namah
Sri Ram

Sri Saraswathi: Om Sri Sarasvatyai Namah

Education and Intelligence

Uthgeetha pranavoth-geetha sarva-vaageeshwara-eshwara sarva vedha-maya-sindhya sarvam bodhaya bodhaya

Saraswathi Mantra: Aum Aim Saraswathyai namah

Saraswathi Gayathri:

Vaag devyai cha vidmahe bramha patniyai cha dheemahi Thanno Vaani Prachodayaath

Good Speech:

Aum Aim kleem sau vatha vatha vaak vaadhini swaha.

Lord Subramanya, Kartikeya: Om Sri Saravanabhavaya Namah

Sharangati Mantra (for surrender): Om Sri Ramah Sharanam Mama
Om Sri Krishnah Sharanam Mama
Om Sri Sita-Ramah Sharanam Mama

Sharada: Om Sri Bala-Parameshvaryai Namah

Tripurasundari: Om Sri Tripura-Sundaryai Namah

Vedantic Formulae: Om Soham hamsoh
Om Tat Tvam Asi

Om Aham Brahma Asmi