If you just can't seem to cram all the RRDtool options into your head, you may find Ivan Zahariev's RRDtool Wizard most helpful. It will help you build these command lines in a snap.
rrd-announce mailing list
If you want to keep up-to-date with the progress of RRDtool, subscribe to this LOW VOLUME list by sending a message with the subject 'subscribe' to email@example.com. Or on the web interface.
Note, that posts to this list will be crossposted to the rrd-users and rrd-developers mailing lists.
rrd-users mailing list
rrd-developers mailing list
If you are interested in working on the RRDtool code itself, subscribe to this list by sending a message with the subject 'subscribe' to firstname.lastname@example.org. Or on the web interface.
Bug Tracking, user maintained documentation and SVN access live in the RRDtrac site. Check it out.
the #rrdtool channel on IRCnet
On IRCnet there is an #rrdtool channel where you can meet fellow rrdtool users online. It has it's own homepage with instructions about how to connect.