Here are some common builds among Colonels:
5 Banger sniper:
http://img91.imageshack.us/img91/8537/20080426174031th0.jpg
http://img216.imageshack.us/img216/5708/20080426174048qn0.jpg
The standard sniper of today, 3 SC200's and 2 Sabres. The placement of the two Sabres varies, but the rest is usually identical. 3 grenades are sometimes substituted for the Sabres.
Naqa legs
Isba spacer
Nobili generator
Brooke cockpit
(3) SC200s
(2) Sabres
you can optionally add a radiator if you think you need it
highest damage CE rounds in all guns, rotated so they're all pointing down and in.
Gator sniper:
http://img214.imageshack.us/img214/1091/20080426175429nb0.jpg
http://img214.imageshack.us/img214/7237/20080426175441qa6.jpg
Used to be the most common sniper, still popular. It has a stronger cockpit and fires 4 SC200s at once, instead of 3 and 2.
Naqa Legs
C110 cockpit
G10 generator
Isba spacer
(4) SC200s
Fidda or AM110 shield plate
use the highest damage CE rounds
Firewalker (aka H-wing howitzer, the A-wing howitzer is similar)
http://img214.imageshack.us/img214/8602/20080426174844mt3.jpg
http://img91.imageshack.us/img91/660/20080426174851hy6.jpg
Typical soldier build with howitzers, they can be attached to the spacer or the cockpit. Usually has Faus howitzers, Espadons are OK too. HW300s are sometimes used but aren't accurate.
Naqa legs
Isba spacer
C110 cockpit
G10 or G100 generator
(4) Faus howitzers
never rotate howitzers.
Lowrider:
http://img214.imageshack.us/img214/7233/20080426174438rq5.jpg
http://img91.imageshack.us/img91/3460/20080426174445ps6.jpg
http://img214.imageshack.us/img214/1268/20080426174535fq9.jpg
Very good mid to long range support, with 4 howitzers and 2 sabres. Not for up close fighting.
Meade treads
Isba spacer
Nobili generator
Johnston cockpit
(4) Faus or Espadon howitzers
(2) Sabres or SC200s
6 Howie:
http://img91.imageshack.us/img91/4759/20080426174708as3.jpg
http://img91.imageshack.us/img91/6516/20080426174716mc5.jpg
http://img132.imageshack.us/img132/8166/20080426174731pz8.jpg
A useful artillery and support mech, but don't run it like a soldier, its not for short range fighting.
Triple Single:
http://img91.imageshack.us/img91/7418/20080426174623up5.jpg
http://img214.imageshack.us/img214/2193/20080426174636sp8.jpg
Common artillery, now that double doubles aren't as good. Better long range than the 6 howitzer, but vulnerable to snipers and anything up close. Asifa's are more accurate, but Bastard's are more powerful. Don't use any other type of heavy cannon on this.
Sidewinder Cannon:
http://img91.imageshack.us/img91/6214/20080426174249bw3.jpg
http://img132.imageshack.us/img132/4904/20080426174302lg6.jpg
Standard cannon hound. Might be a good idea to use 3 cannons and 3 grenades instead. Usually has Falchions, sometimes Anelaces, can also have CN300s if the armor plate is removed. 4 CN300s hurt.
Naqa legs
C110 cockpit
Isba spacer
G100 generator
(4) Falchions
AM110 armor plate
Use highest damage CE rounds if you plan on fighting. KE rounds can kill bases but aren't as good against mechs.
Terror Tower:
http://img214.imageshack.us/img214/917/20080426174129js0.jpg
http://img91.imageshack.us/img91/9828/20080426174139uj7.jpg
Triple heatseeker, great ambush weapon. Its short range and has limited ammo, stay out of open fields. You can build it in many different ways, but the principle is to stack 3 heatseekers vertically and put a cockpit behind it. Use the small Sal Kar heatseekers.
4 Assault Rifle, 3 Grenade:
http://img514.imageshack.us/img514/4131/20080426174212ze5.jpg
http://img258.imageshack.us/img258/139/20080426174218mp0.jpg
Useful for picking away at shorter range mechs outside of their effective range, grenades are very nice too when they close in. You'd need to use AR100s or 200s for this, the Tarakian AR's are more popular but will not fit here.
For further research, there are (slightly dated) guides at:
http://boards2.sega.com/chromehounds_board/
http://forums.xbox.com/464/ShowForum.aspx