Rabbi Yitzchak Twersky, based on the Abarbanel, says that the nachash/snake didn't talk, but that Chava heard her own voice inside her head. Although she should have known better, Chava worked under the assumption that people and animals were the same. She chose (accidentally on purpose) to think that G-d said not to eat from the tree because the tree was poisonous.
She could only accept it in that way and could not accept that G-d said no because people and G-d have a relationship that includes commandments and rewards and punishments based on free will and choices. When she saw the snake rubbing up against the tree she decided that the tree must not be dangerous. Thinking that you couldn't even touch the tree, lest you die, was a logical follow up to the thought that the tree was forbidden because it was lethal. In Chava’s mind, as she saw the snake touching the tree she said to herself, "isn't it true that G-d said that you can't eat from all of the trees of the garden?"
If you read that question over again, you'll realize that one could argue that the answer to the question is yes. Because once you can't eat from one tree then it is true to say that you can not eat from "all of the trees," as you can only eat in fact from some (albeit most) of the trees. That's one possibility of how she got from the one tree to all the trees in the garden, that it was based on her discomfort in having G-d control what trees she could eat from, even if it was only by saying that just one was off limits.
The idea that the snake was actually Chava's voice is applicable today. We weaken in resolve and in responsibility by talking about the yetzer hara as if it were a him, outside of ourselves. The snake/yetzer hara is a metaphor for a voice inside of us that we control. What this means is that the fruit had no power that changed Adam and Chava’s thinking. The powerful force that changed their way of thinking was the act of disobeying G-d and acting based on their own judgment.
This can be understood through the analogy of parents and their son or daughter. If there’s a party and the parents feel it’s best to not go to that party, the child may assume that he or she knows the parents’ reason and that it won’t be a problem to disobey the parents if that reason seems, in the child's mind, to not apply to the situation. If the kid attends the party, he or she will never be the same. It may be that nothing of import happened at the party, but what changes the child forever is the act of trusting his or her own instinct over the authority of parents.
The question that comes to mind after taking in this approach is - why was the snake punished if he didn’t speak to Chava? The answer is that the "punishment" of the snake was a necessary consequence to show Chavah, and to remind people forever, that animals and people are different. Animals were created to serve people so they are "punished" when it's necessary for the sake of people. This fits with what Rashi says about all the animals being "corrupt" and destroyed in the flood; they were only created to serve people and once people were corrupt, there was no use for animals. This also its with the idea that we sacrifice animals (and that the command to do so includes the word Adam!)
One strong indication that the snake never spoke is that when the snake is “punished,” we see no mention of his losing his power of speech. Another hole in the common conception that the snake spoke is that man is described upon his creation as a unique "nefesh chayah," which Unkelus defines as "ruach memalelah" – a speaking soul, clearly implying that man was the only creation endowed with the power of speech.
May we be blessed to remember that as human beings we are unique. May we be blessed to be strong and to honor our relationship with G-d through obedience. May we be blessed to learn from Adam and Chavah’s error, to make the greatest choice we could make, to pursue and hold onto our closeness to G-d.