Send me an e-mail at Homer V P _@t gmail d0t com this is the e-mail I check every day, multiple times per day (except when travelling etc) so I will more than likely respond within 24 hours, possibly even within an hour.
In the website where they are hosted, there should be a "contact the developer" link somewhere (on IndieDB for example it's to the right, under the project stats). If a week has passed and I haven't replied, you may send to my e-mail, but please use the appropriate platform when possible.
There's something other than those?! Alright, use the e-mail. Remember to use a meaningful title, I try to check everything that comes in but if it sounds like a newsletter it might get thrown out.