I have lists targeted to people interested in the following: Adsense, list building, MMO (general). So this may or may not apply to others. Fair warning.
When I include the recipient's first name at the beginning of the Subject of an email, I get a 53% open rate. When I use their first name somewhere else in the Subject, that drops to 46%. When I don't use their first name at all in the Subject, the open rate is 42%.
When I include the recipient's first name in the salutation (Hi _______,) when they open the email, I see a slight drop in unsubs and also a slight increase in the click-through rate to my offer. That's vs. not using their first name in the salutation.
Adding the recipient's first name once or twice in the body of the email also slightly improves results.
Bottom Line: When I use the recipient's first name in all areas: Subject, Salutation, and twice more in the body of the email, I get the best results.
I'm going to test writing styles next. Things like conversational vs. informational tone in both the Subject and Body of my outgoing emails. I'll report results here in September.
Hope this helps some of you refine your list monetization results!