With the recent Week Cal update allowing rolling events to be flexible (i.e., I can set it to roll for 1 day, 2 day, 1 week, 1 month, etc), I am compelled to mention the iOS calendar app Week Cal.
In my Palm Pilot PDA days - I love the calendar DateBk. But after my Palm Tungsten T5 suffers from drop too many drop, I ended up getting an iPod touch and were abhorred with the crappy program that is Calendar. Perhaps crappy is too strong a word - it is just that the default calendar program is exactly what the program name suggested - a calendar. The screen real estate is poorly utilized, and there is a severe lack of features.
After googling on and off for about a month, I was thankful to find this Lifehacker article (here). And for the better, I am happy to have settled with Week Cal by chance.
For those that used DateBk, I love the conditional formatting, templates, and floating events. I use the conditional formatting to mark important or timed appointments (which is useful because I put a lot of other information on the calendar in additional to just appointment. The conditional formatting allows me the highlight the actual appointments. I use floating events also because of the various other information I put on my calendar - so that I do not have to manually roll these events for each day. For those unfamiliar, the rolling event is an option that you can set to have events automatically "float" or "roll" to the following day. Even I first started using Week Cal, they already have the first two features. With the past two updates, the rolling event function is added, making it close to everything I need.