ELJEFE25  This is one of the most useful pieces of software I own. It's super easy to set countdown timers (I've got 5, 10, and 15 minute ones open on my desktop all the time to keep me on task), and it functions as a stopwatch and an alarm clock too. Multiple time zone support, beautful interface, ... what more could I ask for?

The only suggestions I would make would be to add Growl support for notifications, and to drop the price slightly. It's a great piece of software and I'm glad I paid for it, but $20 strikes me as just a bit steep. And yes, there are free alternatives, but I haven't found any that do so much and are so beautifully designed and intuitive.  
(Version 3.3.4)

YOGI COACH  Wow - I'm impressed! I've looked at many menu bar clock replacements, timers and alarm clocks over the years and have found a winner! Meridian is a text book example of a beautifully crafted Macintosh application. It's very flexible and sports a sizeable list of genuinely useful features all wrapped in an efficient, intuitive and uncluttered user interface.  
(Version 3.0)

HARDCAT  I tried all the menu clock applications currently available. I chose to purchase Meridian soon after launching it. Meridian is a great application and it's UI is very pleasing on the eye. In addition to a clock of which additional clocks can be created say for different time zones, Meridian also has user created Stopwatches, Timers and Alarms, so all time related tools are catered for in one application. Notifications and alarms can be implemented via iTunes which is a great bonus. Clocks can be Menu resident or Placed on the desktop like Widgets, and they are rendered wonderfully. Meridian is a great application, buy it and you won't be disappointed.

hardcat  
(Version 2.1.1)

ANONYMOUS  I'm a satisfied Meridian user. Meridian 2 is a huge update from the first version. The new digital clock face is very Tiger-looking. The wakeup feature is going to come in handy. It's slick like a Mac application should be.

In response to the previous reviewer, Meridian really is better than the free clocks, just like Transmit is better than the free FTP programs, and OmniOutliner is better than the free tools. With Meridian you get what you pay for.  
(Version 2.0)

ANONYMOUS  It costs too much. Like any other clock app which is not free.

Besides, there's Aion, showing multiple time zones from the menubar. Free.  
(Version 2.0)

ANONYMOUS  Great update!

OK. It is a bit more pricey than some other clocks, but it also looks better, is stable and has a lot more functionality than most of them.  
(Version 2.0)

TREVOR  Sure, there are other clock programs for OS X, but this one really is the best. The clock faces look great, and the user interface is polished. Everything works like it should.  
(Version 1.1)