Alright, so perhaps you did not start a guild with a group of friends from your work and therefor you do not have any clue what to name your guild. So what do you do? I honestly hate when I see stupid guild names that are cheap ripoffs of other guild names or movies. I think a guild name should be clever. For example, I saw one person who had a Tauren Druid named Skim in a guild called Milk. While I do not picture there having been a large amount of members in that guild, it was original and worked for that person.
On a more serious note, the name of your guild is going to be something you are stuck with unless you want to get a bunch of people to sign another charter and go through the process of changing over for the sake of a name. So what I would suggest is pick a name that sets the tone for what you will be about. For instance, my guilds are named Mass Affluent Slayers and First Bank of Silvermoon. Let's look at the Mass Affluent Slayers first.
The guild started as a joke. None of us planned on it being anything special. It was simply a place to go to and have a good time. We did, however, debate on the name and chose the Mass Affluent because of the function of our business, but the Slayers we chose because the majority of us loved the PVP aspect of playing WoW. So we combined those two ideas and created Mass Affluent Slayers. In retrospect, the First Bank of Silvermoon was created as a way to get more bank tabs at a cheaper cost. I simply explained what I was wanting to accomplish and selected the officers to offer up one alt to sign the charter and we created a guild soley for the purpose of storing materials and equipment at a cheaper price. I took it one step further and moved all my auction house characters there as well. Thus the name First Bank of Silvermoon represented what we needed to achieve with this particular guild.
There is more to the name of the guild though than just a purpose. We built the whole idea of our ranks around the thought of the guilds being based on business models. So again, the name of the guild will play an even bigger role in deciding other aspects of the guild as well. So in closing, I cannot tell you what to name your guild, but do keep in mind that the guild will represent you and your friends and that if someone asks why you named a guild something, then the answer will have some meaning to it other than "it was cool at the time".