Known bugs:

Mirror mode cannot do stacking graphs

The Average line in userdefined graphs treats 'unknown' data as zero.  Should
not count unknowns, and give itself unknown if all data sets are unknown.

The system should be able to correctly cope with a target name starting with 
an underscore. 

The verify page creates a special png file in the graphs dir, but cannot 
delete this or prevent it from being cached.

We need to add the new headings to the icons sets in the altgif directories

Not all MRTG directives are fully supported (Tobi keeps adding new ones!)

Under Windows, the lack of variable timezone support prevents the time zones
from working correctly.  No way around this, unless rrdtool is changed!

The working day averages on the daily graph get upset when it's the weekend
and no working day is visible.

Routingtable extensions have been reported to cause problems under Netscape,
but unable to duplicate this.

Authentication seems to expire even when it should not.  This has not been
successfully duplicated, yet -- may be due to client clock synchronisation?

File-based authentication is not so wonderful, but seems to work.

When using an Extension, there is no guarantee that it will be friendly and
reset the Target menu.  Maybe provide a wrapper?

Script should check the GD libraries and use PNG/GIF depending on which
version we have.  Install should also check this and set appropriately.

Install does not fully set up the authentication for you.

cfgmaker-host needs more for interfaces, and more support for other SNMP
agents.  Seems to hang with AIX agent for some reason.

mrtg-pnsclient does not give correct CPU figures, I think.  But I may be wrong.

Strange effect sometimes removes Y-Axis scale.  Rescaling fixes it.  Not clear
what causes this, may be RRDTool bug? (Identified:  This is when using fixed
mode, and the number is >6 digits long.  Cannot be corrected - RRD problem)

Language support is a bit patchy.  Cannot have non-8bit-ascii characters in
the RRDTool graph image.  Also, if you have multiple languages in use on your
system, then trendurl and routingtableurl can cause odd behaviour if used
in the routers2.conf in conjunction with caching mode.

Performance is getting rather bad if you have >500 cfg files and do not use
some sort of caching with mod_perl or speedycgi.