Shiva: Simultaneously, the destroyer and creator of the universe. Shiva often appears dancing within a ring of fire. Natarajasana (dancer's pose) is a reference to Shiva.
Ganesh: The popular elephant-head god, who has a good sense of humor. Ganesh is playful but protective (like a kind and earnest older brother). He is known as the guardian of the threshold. For that reason, a sculpture of Ganesh often greets guests in the doorways or foyers of homes or businesses in India.
Krishna: The blue god. He is often seen playing the flute. In the Bhagavad Gita, he is portrayed as a young soldier seeking guidance.
Durga: The warrior goddess. She rides a tiger. A complete badass. You might choose to invoke her strength the next time you are in Warrior II pose.
Lakshmi: The goddess of prosperity. She is typically portrayed sitting or standing within a lotus blossom. She represents abundance, blessings, wealth, and well-being. For those of you seeking to solve your financial troubles or break a cycle of poverty, debt, parking tickets, etc. find an image of Lakshmi and place it somewhere in your home, where she is readily visible to you (e.g. the bathroom mirror, closet door). Invite her powers into your life. The more you envision yourself supported by an expert/god/guardian/etc., the more confident you will feel in your ability to affect change in a certain area of your life. Try it!
Saraswati: Goddess of literature, learning, and creativity. She's my favorite. Children in India pray to her before exams, and I keep a statuette of her by my laptop while I write.