OpenCRX

openCRX is an Open-Source CalDAV and CardDAV server.

Setup

follow instructions in the openCRX Admin Guide to setup/configure a CalDAV collection
use the Wizard "Connection Helper" to get the URL of the CalDAV collection, e.g.
http://demo.opencrx.org/opencrx-caldav-CRX/CRX/Standard/user/guest/profile/MyCals
then, on your Android device, add a new CalDAV-Sync account and enter
Server name: the URL of the CalDAV collection (w/out the leading "http://" or "https://"), e.g.
demo.opencrx.org/opencrx-caldav-CRX/CRX/Standard/user/guest/profile/MyCals
Use SSL: check accordingly
Username: your openCRX login name
Password: your openCRX password
click Next
choose the sync feeds you want to synchronize (typically, you get 2 feeds in CardDAV-Sync per openCRX feed, one feed with "Todos" and another one "Events")
click Next
enter the e-mail address associated with the CalDAV collection (e.g. yourname@yourcompany.com) and indicate whether you want to enable two-way sync or not (note, however, that two-way sync will only work if the approprate options are also set at the feed-level in openCRX)
click Finish

CardDAV is supported with openCRX v2.9.2+ (not available from Sourceforge yet...)

use the Wizard "Connection Helper" to get the URL of the CardDAV collection, e.g.
http://demo.opencrx.org/opencrx-carddav-CRX/CRX/Standard/user/guest/profile/MyCards
then, on your Android device, add a new CardDAV-Sync account and enter
Server name: the URL of the CalDAV collection (w/out the leading "http://" or "https://"), e.g.
demo.opencrx.org/opencrx-carddav-CRX/CRX/Standard/user/guest/profile/MyCards
Use SSL: check accordingly
Username: your openCRX login name
Password: your openCRX password
click Next
enter the name associated with the CardDAV collection (e.g. contacts/demo) and indicate whether you want to enable two-way sync or not (note, however, that two-way sync will only work if the approprate options are also set at the feed-level in openCRX)
click Finish