Here is a synopsis of laxative types that I ran onto today on an IBS website:
Over-the-counter Products
OTC products such as laxatives and fiber supplements are intended for temporary or occasional use. You should always observe the safety information of any OTC product.
OTC Laxative Products for Constipation
Bulk-forming laxatives
These laxatives, also known as fiber supplements, work by absorbing water in your intestine, thereby helping to make your stool softer. These laxatives must be taken with water. Products include Metamucil® and Citrucel®.
Stimulant laxatives
These laxatives cause rhythmic contractions in your intestines. While effective for relieving the symptoms of short-term constipation, they could be habit forming with the potential for abuse. Products include Correctol® and Dulcolax®
Osmotic and saline laxatives
Osmotic laxatives and saline laxatives act like sponges to draw water into the colon to help make passing stool easier. Examples include Milk of Magnesia®, Phillip's M-O®, MiraLAX® and Kristalose®.
Lubricant laxatives and stool softeners
Lubricant laxatives grease the stool and enable it to move through your intestines more easily. Mineral oil is the most common lubricant laxative. Stool softeners help moisten your stool and prevent dehydration.

chart about various kinds of laxatives:
http://www.miralax.com/pdf/Comparison_of_constipation_treatments.pdf?utm_source=WebMD&utm_medium=banner&utm_term=WebMD_Custom&utm_content=Display_WebMDMiraLAXDest_ICM_link1&utm_campaign=2012_MiraLAX

Here is my regimen, which works most of the time. If it worked 100% of the time, I wouldn't be here. I try to eat plenty of fiber but my work schedule makes eating properly very tricky. So, every night, I take one coffee scoop (2 tbsp. or so?) of generic Metamucil plus one cap full (again about 2 tbsp.) of generic Miralax. The only way I have found that I can take psyllium husks is to mix with either grape juice or soy milk. Now that soy milk may be contaminated with GM strains, I use grape juice. I pour grape juice over the generic Metamucil and Miralax, then microwave for 25 seconds, then stir vigorously. Microwaving brings the juice up to room temperature and prevents clumping that occurs with cold juice. This usually causes me to have bulky and soft (but not runny) stools. If my system needs a little boost, I add 2-4 Phillips Caplets. If it needs a major boost, I take half a bottle of liquid Citrate of Magnesia. I try to avoid Dulcolax and other stimulant laxatives because they give me mild to severe cramps.