I appreciate correspondence from people who like my work, those needing assistance, and even those who just feel the need to send me a message. If you have a request, bug report, suggestion or anything else really (other than spam!) then send me an email and I'll try to get back to you as soon as possible.
Before you email however, please take a moment to check if your message would be better sent via an alternative communication channel - for example, some of my projects have dedicated public mailing lists, where discussions can be made in public for the benefit of others. Alternatively, if you have a general AVR question that anyone competent in AVRs could answer, your question might be best posted over at AVRFreaks.net. I'm there too, under the username abcminiuser.
I am also usually hanging around the #avr IRC channel at Freenode under my abcminiuser nickname during the week - join the room if you want to have a real-time chat with me and other AVR engineers.
For those who really like the whole actual voice communication thing, I'm also on Skype occasionally (username abcminiuser, of course) and available for a chat.