http://stickgrappler.tripod.com/ - a site with some links to pad drills, counter drills etc. There are some good drills under the boxing section too.
My favorite pad drills are free flowing ones. Where you partner can call anything and fire off attacks at you, you counter and fire back. Basically, it looks like the two of you are sparring, one just has thai pads and a belly pad on.
The pad holder has a belly pad and thai pads on (maybe shin guards as well), you have a mouthpiece, gloves, headgear and maybe some shin guards. Your partner can hold up anything he wants or call out any combo's he wants, you have to fire them off. At any time, your partner can fire off an attack at you, you have to block, slip, parry, or evade the attack, then counter attack. This works better if you have a set way of holding for the attacks. Ex: We always cross pads on punches, meaning the right hand punches the pad on the right hand. Hold the thai pads so they are facing down a bit, obviously not ready to take a shot. When you want a jab, you hold the left pad up. A cross -the right pad, a left hook- the left pad held verticallly facing to the side, rt uppercut - right pad held horizontal in front of holder. Pads down at side facing backwards- push kick, pads to right or left - corresponding round kick. You can sub in an elbow for any punch at close range and a knee for any kick (just work out the kick/knee ahead of time, the hold is different).
EX: Get a couple of counters worked out in isolation that you really like and work then into your pad drills. So your partner is calling off or presenting for certain strikes (calling out for combos works best if you can name them, like "1" for a jab right kick, "2" for jab, cross, left kick, etc). Your partner calls a 3 - for us that's a jab, cross, left hook, right round kick. After the round kick hits, my partner throws a right cross at my chin (like he was countering my kick), I bob left, fire off a hard left hook to the body, double up with the hook to the head, a right cross and finish with a left kick/knee. We keep on moving and chanign angles, distance, etc. The closer it resembles a fight, the better it is.
Once you get comfortable with the drills, your partner should be throwing fast. If you aren't getting hit with some of those punches and kicks he's throwing, then you aren't doing it right.
Some of my favorite counters:
Jab - parry with right hand while throwing a left jab of your own, slide off angle a bit, then fire the overhand right, left knee/kick
jab, Cross - Parry jab, bob your head to the left of the cross, counter with left body hook, left head hook, right cross, left knee/kick
Jab, Cross, left hook (head) - Parry jab, bob left cross, hard block with right hand for hook while throwing a left jab into their face, right hook/elbow, left kick/knee
Right Low Kick - block, then touch and go left round kick - set your foot down so you are standing southpaw for a split second, just long enough to use the contact to throw you into the kick
Left low kick (usually to inside of lead leg), block with left shin, cross, hook, right round kick
Right High kick - Either evade back and right round kick, or hard block and left round kick.
Left High kick - Either evade back and right round kick, or hard block and right round kick.
You can make up any counter you want as long as you think you can pull it off in sparring.
Sparring - you can actually get a lot of good training out of sparring light, make it light ot no contact, work on counters and setups for attacks. The goal isn't to hit your opponent so much as to not let him hit you and to figure out HOW to hit your opponent using angles, setups, etc. It will help you work on your timing a bit and get you used to having punches and kicks coming at you without freezing (not as well as real sparring, but it will help). The lack of hard contact will let you make mistakes without hurting for them and not make you afraid to try new things. It will also let you watch your partner and help them by pointing out holes in their offense or defense while they are countering or comboing.
Hope this helps some.
....... and Muaythai thought he wrote a novel.....