I've played a side snare (and even a configuration that had a 6", 8" and 10" micro snares on the side on a rotating stand)
for a long time and love the flexibility of the sound.

For one thing, you can make each song in a set sound different and you can navigate between different styles
without always having the same kick, hat, snare sound (while you are at it, it's also cool to use 8" and 10" closed
hi hats around your kit for the same purpose).

Additionally, it's really cool to play sixteenth note single stroke rolls in a groove, where the right hand plays 8th notes
on the hi hat, (coming down on the backbeats on the deep front snare) while the left hand plays ghosted notes
on your side snare). Alternating between using those left handed ghost notes on either towards the rim
of your primary snare or anywhere on a higher pitched side snare can cause really great percolative grooves.

Viz a vis, finding drums, the nice thing is that in order to be timbrally effective, you want a fairly significant tuning
range between your lower pitched primary snare and your higher pitched (or lower pitched) side snare.

Since cheaper drums sound a lot better at higher tunings, you don't have to use a great snare drum to have
a very effective 'piccolo' or 'hip hop' sounding hi pitched drum.

What I did was use three fiberglass 70's Pearl concert toms which I then customized with bottom rims (that I drilled holes
in to accomodate snare ties) and used piccolo snare mechanisms to add to the drums.

Nowadays you can buy pre made 8" and 10" snares for your drums (though I had to cut normal snares off of 14" drums and
resolder them in order to make my 6" snare drum work) and you can even find 8" and 10" snare sides as well.

Throw on a cheap tom tom mount and you can mount the drum straight to your hihat with a normal clamp.

Pearl, Tama and Gibraltar all make parts that can work.

Or, you can buy pre made snares for more money. If you don't mind mixing and matching the look of your kit
, there are a lot of clear plexiglass snares out these days that sound killer and really project even in the smaller
8" sizes.

One warning, however: smaller drums like 8" don't project as well as 14" drums so you may need to use a microphone
to amplify it.

I use a side snare. Its smaller size means a higher pitch, and I keep it tight so it is really a sharp sound. My guitar/band leader actually loves this little snare and often has me use it over my main snare. I think he likes how it cuts through on loud songs as well as still being quite audible even on quiet songs.

Recently I changed the angle of my main snare so it is essentially flat. It makes hitting a rim shot much easier. I also adjusted its position slightly so it is easier to hit right in the middle, for a sound without as many harmonic overtones (much cleaner sound). Now my band leader is back in love with my main snare... I think what he really wants is for my snare to cut through everything.

The other thing about the side snare is that it is on the left side of my hi-hat (I have a standard right-hand kit with a HH on the left and the main snare just to the right of the HH). The side snare on the left of the HH allows me to play different rhythms without a cross-over. That is, I don't have to cross my hands to play and for some rhythms this is useful. In particular, the side snare makes it easy to play intricate rhythms because it is so close to the same height as the HH that the sticks only need to move about 2" total. My regular snare is farther away and, well F=MA limits what I can do, especially for low volume intricate stuff.

LeDude,

I have collection of 12 snare drums now and only one of them is 14" in diameter, so I guess I like smaller sizes! Most basket type stands will only accommodate 12-15" drums so most smaller 8-10" drums come with a mount on the side for a L-arm style holder. A 'RIMS' style mount can also be used. My current configuration has three snares as I play a lot of jungle and world-fusion styles I rely on many snare sounds available. I have a 10" mounted to my left off the hi-hat stand with 13" main and 12" off to the right where a second floor tom would traditionally go. Some folks mount them higher like tom-toms too.

I have had good luck with the both theTama Artwood and Steel models - I like the 5.5x12 hammered chrome and 5.5x10 maple the best. For a drum that can easily be used for a main or 'side' snare the 4x13 or 6x13 Artwood is a bargain on ebay for around $150. Pork Pie and Pacific also make a few that are affordable. The Gretsch 'Blackhawk' models are a little shintzy and I sampled mine then sold the drums (8" & 10"models). My favorite are probably the Pearl 3x13 brass and Ludwig 3.5x13 bronze which is an amazing drum that runs about $200 on ebay. In my experience, most of the cheaper snares need the heads and snares replaced to sound good.

Hope this helps!