I've been using AquaticLog for about two years now; interface is simple to use and there are a lot of handy features. Really like the reminders for things I dont do often (i.e. replace the T5s or clean the LEDs).
I have a great excel spreadsheet with all sorts of graphs and calculators that I got from someone on another forum years ago. If anyone wants this pm me your email address and I'll gladly send it out to you.