- Five countries that end in the letter L: Brazil, Israel, Nepal, Portugal, Senegal
- Three countries that don't contain any of the letters in the word "mackerel": Fiji, Togo, Djibouti
- Nine countries that start and end with different vowels: Eritrea, Ethiopia, India, Indonesia, United States of America, Uganda, Equatorial Guinea, Estonia, Ukraine
- Thirteen capital cities that start and end with the same letters: Asmara, Addis Ababa, Accra, Andorra (la Vella), Abuja, Astana, Apia, Ankara, Oslo, Tashkent, St George's, St John's, Warsaw
The winners are:
crystalpyramid (who got an impressive nine of the thirteen capitals)
Since this was pretty difficult, I'm happy to send rewards to everyone who gave it a go. Just let me know a snail mail address (if I don't have it already) via comment or PM and I'll pop something in the post for you. Comments are screened.