Bruce wants to work at the Exploratorium as a docent. He sends this email cover letter to entice the reader to download his attached resume. A big part of why this email cover works is that in just a few short lines, Bruce reveals his humor and personality, which are key to being a good docent.
Here's another thing Bruce could have done: He could have attached a formal cover letter. He chose not to do that because the docent position he is going after is part-time, volunteer, and casual. It just didn't seem to call for a formal letter, so he opted for this light-hearted email instead.
Take a look. Maybe there's something here you can use in your cover email.
I found your job listing on HotJobs.com for a docent. Do you need someone who is flexible, professional, creative, and a great team member? Someone with a passion for science and education who loves answering questions? If so, I'm your man. I grew up in a family of scientist-educators and I have a "dinner-table-lecture-series degree" in science.
I am attaching my resume for your reveiw. I look forward to discussing with you how I can be of help to the Exploratorium.