As someone who has a regular schedule of weekly meetings and appointments — work meetings, after-school sports for my kids, and so on — it's always helpful when someone who wants to schedule a meeting with me mentions the day along with the proposed date and time. For example, when I'm asked if I'm available on May 6 at 3 p.m., I have to look at my calendar; but if I know that May 6 is a Tuesday, I can immediately reply that I can't do meetings after 3 p.m.
Which brings me to my biggest gripe about OS X's Date & Time menu-bar display (enabled in the Date & Time pane of System Preferences): It shows you only the current date and time. There's no option to display, say, a monthly calendar when you click in the menu bar. Sometimes I'm on the phone or writing an email to set up a meeting, and I'd like to know what day of the week a proposed date falls on — since I'm no calendar savant, I need to look it up.
Thanks to Day-O, I have just such an easy-access calendar. Shaun Inman's free app — which he developed after the demise of MenuCalendarClock — is as simple as they come, but it does exactly what I need it to do, and I've been using it for a couple of years.
With Day-O's calendar open, you can click right and left arrows to shift the view forward or backward a month, and click the circle in between to quickly return to the current month.
The only real customization feature is a nice one: support for Unicode date-format patterns for modifying how the date and time are displayed in your menu bar. For example, I use h:mm a on' MM/dd/yy, which displays the date and time as shown in the screenshot above, but you can use a variety of different patterns. For example, h:mm a displays just the time (12:00 AM, for example), while EEE, MMM d, yyyy G gives you "Mon, Mar 24, 2014 AD". The Unicode Locale Data Markup Language website has a section on date format patterns with the codes and patterns you can use.
Day-O doesn't do much else. In fact, there are several other calendar apps — including the excellent Fantastical — that provide an on-demand calendar and much more. But if, like me, you don't need all those extra features, Day-O works well, and it's free. I use it daily, and it's a valuable part of my Mac setup.
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