Where can I find medication absorbiton charts?per rectum, ingestion(oral),intravenous...

I am sorry to report that you will likely be unable to
find an absorption chart for all drugs in general.  This is because the absorption rate
of drugs is affected by many, many variables, among which some are listed as
follows:

1.  The form of the drug (tablet,
capsule, sustained release, etc.)

2.  The
pharmacokinetics of each particular drug, no two drugs having identical features. 
Pharmacokinetics deals with the chemical composition of the drug (such as acidity or
alkalinity), method of absorption into the body, effect of other drugs and food,
distribution of the particular drug to organs in the body once it has been absorbed,
bioavailability of the drug to the tissues once absorbed, metabolism of the drug within
the body, half-life and excretion of the
drug.

3.  The route of administration of the
drug (oral, rectal, intravenous, intramuscular,
etc.)

4.  And many
others.

Peak and Trough drug
levels:

One can get an idea of absorption time for drugs by
measuring blood levels of the drug at various times following ingestion or injection. 
One should study the peak level (maximal level attained for a given dose), the trough
level (lowest level measured between doses, usually just before the next scheduled dose)
and therapeutic level (the level which has been determined to provide the best intended
medical effect).  By knowing the times for peak and trough levels you can get a good
idea about time of absorption.

Absorption tables
are available for specific drugs or small classes or groups of drugs, but I have not
found tables that list hundreds of different
drugs.

The web links given here amplify these
concepts.

The first gives peak and trough times,
therapeutic and toxic levels and half-lives for a large number of drugs.  It may be the
closest thing to the type of table you seek.

The
next provides basic information on drug metabolism, bioavailability, distribution in
tissue and excretion.  It will clarify why the table you seek is unlikely to be
found.

The last is a veterinary article that
just happens to give an excellent basic general discussion of important concepts such as
drug absorption, clearance, volume of distribution and
half-life.