Two pet peeves I have.
1. Official business mailings, documents and emails with basic grammatical and spelling errors.
I am a high school graduate, I could not cut it in college but I can usually spell relatively well and in the cases I can't I leverage the tools modern technology has given us. I am astounded at the number of business communications I get which lack basic grammar and spelling which are written by COLLEGE GRADUATES.
2. Electronic communications using non universal distribution media.
If a company is going to send out mass mailings with "Important information on how to do XYZ," or "New sales incentives." It is a good idea to make sure the attached information can be read. Not everyone is using Office 2007 (I know it's a shock) so maybe you should use some converter to change it to a PDF or something easily read universally. It is easy to do a Google search for free PDF converters and find several.
OK, I feel better now.