Over the years, I've owned/used a number of different multimeters. I'll skip the details of them though and get to the one (I have two of them actually) that I use most often and carry with me when out riding.  It's the Radio Shack 22-820.


(It also comes in yellow.)

Pros:


* Compact and self-contained.  Only 4.25" x 2" x 1" so it doesn't take up much room in your tool kit or tail cowl.

* Automatic power-off. Not only does this help to conserve its batteries but, if you're like me, then occasionally you use a multimeter and forget to turn it off.  And there's nothing more frustrating then having it be dead the next time you need to use it.

* Auto-AC/DC/ranging/polarity/resistance.  Unlike dial type multimeters where you need to select AC or DC and pick a voltage range, this detects all of that for you.  If you have the DC voltage polarity backwards then it puts a minus sign in front of the reading so it really doesn't matter which way you connect it.  It also auto-ranges when measuring resistance.

* Audible Continuity Tester.  In continuity mode it beeps when there is continuity. This is a very handy feature because you can quickly test for continuity without having to look at the LCD display.

* 20" Test Leads. From the unit to the tip of each test lead. For a multimeter this compact, that's pretty good.


Cons:

* Case Latch. The latch to keep it closed isn't all the great.  However, this is easily overcome by keeping it closed with a rubber band.

* LR44 Batteries. Though common and not that hard to find, small "coin" LR44 alkaline batteries are not as convenient as multimeters that run on AA or AAA batteries.  That said, since it uses three of them and has auto power off, it will last a good long time on a set of them. It also wouldn't be as compact if it used larger batteries. It has a low battery indicator on the display too.

* Display Not Backlit.  This is both a pro and a con.  On the one hand, you need some light on it to read the display when working in darker places. On the other hand, it means the batteries last longer.

* Quality? Out of curiosity, I skimmed the reviews of it on the Radio Shack website.  There are several reviews stating that it failed more or less right out of the box.  However, it's important to remember that people are much more prone to post a review of a product that broke than a product that worked as expected.  And the two I own have been dropped, bumped around, used, abused and ridden in my tail cowls for many, many miles and I've never had an issue with either one of them.  As you can tell from the picture below, the one that was once a nice clean bright yellow when I got it has since "been around the block" a few times. I also bought both of them used on Fleabay so the original purchaser, not me, got to find out if they had quality issues or not.

And it only has a 90 day warranty so be sure to break it quickly and send it in for replacement right away!

I also carry a pair of alligator clipped wires. (Made from genuine BMW wire!) Dollar bill included so you can see how compact it is.


http://www.ebay.com/itm/22-Range-Pocket-Digital-Multimeter-2266866-/400665937603?pt=LH_DefaultDomain_0&hash=item5d498d06c3

Thanks Duck. This is exactly what I am looking for to keep on the bike.

I've had the Radio Shack predecessor of this mm for something like 16 years and I love it.  The hinge on the case failed fairly soon but, like you I hold it all together with a rubber band.
Caught out without it and in need of a mm, I found one of similar size that I really like too.  It's a Craftsman, but I bought it at Ace Hardware in Oregon. It's just very basic, like the Radio Shack item, but it does come in a nylon case that has no hinge to fail   
Both are winners though, and perfectly suited to keep on the bike.

Good work Duck; just the thing you need to carry on your bike.

I recently bought a new MM and it has a continuity beeper. How useful is it! It makes chasing faults so much easier. I should have had one years ago.

Thanks for the link too.

The little Radio Shack mm has an audio signal on continuity too!  That is a very handy feature.