I posted this in freshwater as that is what I currently run, but it applies to saltwater as well. I ran across a neat little piece of software (Mac only. Sorry Windows users.) that allows you to track your aquarium stats. The cost seems a bit high though for what you can do in a spreadsheet with graph capability. Still, it's worth a look.
Support for lunar cycles
Ability to add pictures to your livestock log and Tank
Support for X-10 and macros
User definable global and tank based Min/Max values for water parameters
My Reference Section - Users can create a personal reference database that can be easily submitted to the master shared database
Equipment tracking using a device manager style interface
Save/Export water log to import into excel or other spread sheet
Detailed Reporting of all Logs
Easy Reference Search and browsing with filtering and listing features
Health Log for tracking the health of your tanks and their inhabitants
Livestock Log divided into 4 Categories for Fish, Coral, Inverts, Plants
Quick summary view of last PH, Temperature, and water change from General Tank View.
Easy Conversion Tool of common measurements using in Aquarium hobby.. Cut and Paste values into your logs
Easier to Customize with Grid sorting features
Single window "Outlook" style interface
Ability to print full list of Reference Database items
Automatic calculation of average and standard deviation values for all common water parameters.
55G Filstar XP3 - 16" Fire Eel
75G Medium Planted - Filstar XP3 Low Light - Established Feb 2006