I use e-mail as the main channel of digital communication and my e-mail address is the same as the domain on which you are reading this, just replace the first dot with the @ sign (or just click on the link at the bottom of the page ;-).
For instant messaging (IM) I prefer Jabber/XMPP and you can find me under the following Jabber ID (JID): 4ndY@krizevci.info.
My micro-blogging account is located at Identi.ca (a pump.io instance) firstname.lastname@example.org, but I rarely use it.
You can share files with me via ownCloud/NextCloud: Share.
For my scientific identification, I employ ORCID: orcid.org/0000-0001-9009-8379.