There are an abundance of answers given to this question, including those listed by Alex.
You might like the approach of Abarbanel, who sees no reason to assume that "elokim" is plural, since it is used as a name, like Ephraim, Mitzraim, or Chushim, which are all names in the "plural form". Rather he prefers the explanation that "elokim" is a composition of "el" meaning "god" in a general sense, and God's specific four-letter name ykv"k. (The me"m at the end of the name is to be grammatically correct in "closing off the word" so it won't sound like a possessive noun.)