Ten Things to Help You Time Your Work Sessions
This 
aquarium timer from Onlineclock.net provides a nice fish tank backdrop.  The alarm when the coundown ends is like a digital alarm clock.
For a guided, one-minute exercise workout, try e.gg.timer.com's 
morning warm-up timer (always check with your doctor first if you have a condition that could be aggravated by exercise.)
Want to use Google Search as an online timer?  
Here's how.
OnlineMeditationTimer.com provides a timed sessions with a nice background chime for your contemplation.
You can set the 
Online Stopwatch to countdown any time interval you'd like.  It ends with a ringing bell sound like an old alarm clock.  The site also offers a bunch of different timers.
Onlinetimers.com has a variety of pre-programmed times you can use in addition to customizing your own; the alarm sounds like a low-volume digital alarm clock.
Pomodoro is what I personally use during my writing sessions to remind me to stop, get up, stretch, etc.  It silently runs for 25 minutes, then sounds a alarm (I use the Brrrrrrring option) to remind you to take a five minute break.  After four such intervals gives you a 15 minute break.
Want a little fun with your timer?  This 
robot-race timer is cute.
For the multitaskers, 
Timer-tab.com offers countdown, alarm clock and stopwatch timers
Set 
the Vclock timer to countdown your session and pick your own alarm sound (I liked the wind chimes.)