I am using Mozilla Thunderbird for managing my various email accounts. I was not happy with the default theme for Thunderbird. My search for good theme ended with the wonderful theme Crossover. A screenshot of Crossover theme is here. I would recommend it those of you who use Thunderbird for email. A complementary theme for Mozilla Firefox is iFox. A screenshot of iFox theme is here. Both these themes are available here. Both these themes have look and feel of a Mac OS appliction.
For my blog template, I tried various template provided by The Blogspot, but did not seems to like them. My search for a good template for my blog has ended with Free Blogger Templates. I have modified Aqua template for my blog. I am now quite happy with this template.