The ABAP example program listed here uses the CALL FUNCTION found in 'SE37'.  For e.g. ALV. 
Function modules are procedures that are defined in function groups (special ABAP programs with type F) and can be called from any ABAP program.  All functions can be found at transaction code 'SE37'. 

If you need any ABAP help, do feel free to asked it in the Abapers forum.

ABAP Short cut Links
ABAP Tips and Tricks - ABAP Questions  -  Sapscripts Tips
BAPI Programming Tips  - BDC Programming Tips  - Smartforms Tips

Icon
Creation Of Active Icon

Dates
Pop a Date in Selection Screens
Function to return next business day
Find the diff. between two days in days, months and years
Convert Current Date to Current Period
ABAP Program: Output of Date Format
How to use function  DATE_GET_WEEK
FM to Get the Day for a Particular Date
Determine Last Day of the Previous Month
Date, Month and Popup Related Function Modules

eMail and Faxed
Sending mail with attachment
Sending mail with attachment report in Background
Sending External email through SAP
How can you send a fax from within ABAP/4 programs
Make E-mail Sender of PO the PO Creators Name
Sending Mail When The Purchase Order Is Released
Sending Mutiple Excel Sheets As An Attachment

Microsoft Windows, Office
Create Pivot Table in Excel with Desktop Office Integration
Use SAP code to list how many docs in folder on your PC
Uploading data directly from Excel file format
Uploading multiple multitab Excel sheets or Ranges
Excel Upload Alternative - kcd excel ole to int convert
How to Open files from presentation server with MS Word
Get the windows registry value
Sample Coding For Converting Into PDF Format

Processor Control
Prev. prog. have more than one instance running same time

SD Relevance
User Status Controlled When Sales Order Created

PM Relevance
Post Measurement Documents To Notification

HR Relevance
Function Module To Return Head Of Organisation Unit
Sort Employees As Positioned In OM Structure
HR Report To See Description Per Qualification
HRCA_COBL_CHECK - Cost Assignment Validation Checks
Working Days Between Dates Using HR Calendar

ABAP Objects
What are ABAP Objects?
ABAP Obj. Oriented SpreadSheet with "Unlimited" Power
Bus. Add-in Understand ABAP OO Interface Concept
Splash Screen in ABAP using OO
Reading attribute of a BOR (Business Object)  in ABAP

Upload and Download
GUI_* WS_* Function In Background, CSV Upload
Download in Background in Excel Format
Download/Upload Favorites from one PC to Another
Download/Upload ABAP program from Local Harddisk
LSMW and FTP Upload Chinese Or Non English Characters

Sap Abap Command Reference

SAP Smart Forms

Graph/Image
Creating Chart in ABAP
Use BDS to Store Files Like Excel JPG

Hierarchy Tree
A sample Tree Programming
How to Create Tree Control

Conversion/Numbers
Converting Number to Words
Convert Month to Word
Convert Spool List to HTML
Insert a special Tab Delimited Character
Print Number Value Without Thousand Separator
Fig. to Words for India can be modified to any req.
How can I get Ascii value of any letter
Program For Printing Prime Number
Convert One Currency To Another

Reading Text
Use FM READ_TEXT to Read the Various Text
How To Print a Header Text

XML Example
XML file to word document through SAP
Sample XML Source Code For SAP

User Prompt and Pop Out
ABAP POP-UP Window
Pop-out box for user confirmation
Pop a Message to specific SAP users
Value Request For Parameter
FM VRM_SET_VALUE To List Box
Function Module for Encryption and Decryption
Program To Change Text Into Password
Take Values from Selection-Screen and Issue Message
How to Restrict the Select Options
Using Function Modules F4_FILENAME
Program To Mass Reset Users Password

SAPGUI
Make your SAPGUI Disappear and Appear Again

DOS
To execute a dos command from ABAP
Execute DOS Command in SAP Version 3.x
WS_EXECUTE to called External Program

Auto Refresh
ABAP Timers and Auto-refresh

Calculaor
A SAP Pop-out Calculator

Server
RFC Call to Get Server List

Unix and FTP
Issuing an Unix Command from ABAP
SAP FTP Functions

Functions Overview
List of ABAP Functions

Idoc
Reads Idoc Dispays Contents in Spreadsheet Format
Program To Generate IDoc

SAP ABAP Forum at the convenient of your mail box
Exchange ABAP programming problems/solutions, program, tips, ideas with other ABAP peers from around the globe.
Note: An Auto Free ABAP Tips Windows Help File will be send to you upon Joining. 

Main Index
SAP Basis, ABAP Programming and Other IMG Stuff