Reporting in SysAid is a tricky art, not easily mastered, it certainly took me a while, but here to help you along is a summary of some good threads on the topic:

Report customization is only possible in SysAid full edition with the manager portal.
Reports customization requires some programming skills and you can find most the needed information on how to do it in the manager portal guide which can be found at: 

Ilient can also customize the report for you as a custom development project.
For more information, please contact with your request and they will provide you with all the information on this option.

Common Questions

Which version of JasperReport/ireports to use - 
Using logical conditions in your select statement within ireports and SysAid reporting - 
What does the union field mean in the "workload by administrator" report -
How to extract the inventory_xml data -

Known Issues

Report Fix: "Categories with the most SR's" -
Report fix: Software/Hardware inventory duplicate listing fix -
Problem with angle brackets being interpreted as html tags - 
If you want to use the Service Breach Report based on due dates you are going to need to follow the modifications here - because it is based on timers
Satisfaction by category report average is wrong - Fixed in v
5.6 +

Feature Requests

Scheduling Publishing of Reports - (Not scheduled emailing of reports which it can already do)
Change "Days" in Service Quality Reports to "Hours" - 

 Report Samples
From Haim:

Adding your own company logo to SysAid's reports -
Removing the windows hotfixs from the "asset changes" report - 
Creating a basic report "service request list" - 
Changing the reports page size - 
Add grouping by admin group to the "Service Quality By Timer" report - 
Running the "activities by administrator" report for all administrators at the same time - 
Create a report "Opened/Closed Requests Per Department" - 

From Techguy:

Active Requests report - Group Selection by Status - 
Service Requests Opened by Administrator - 
Report: Active requests vs Date - ( I did not get round to finishing this report -maybe one of you will) -
Modify Activities by User report to report on one of the custom fields - 
Asset Details without Software - 
Due Date Changes Report - 

Debugging Tips
When trying to debug reports you need to look at the sysaid.log file to find the real errors.

 2008-11-03 13:17:30,959 [Thread-5] ERROR com.ilient - Exception while trying to compile report codeorg.xml.sax.SAXParseException: The content of elements must consist of well-formed character data or markup. This is related to the bug with the angle brackets being interpreted as html (see known issues above for the answer) 
net.sf.jasperreports.engine.JRException: Attribute value "Your Report Name" of type NMTOKEN must be a name token. When creating a report Jasper Reports do not put spaces in the report name. TO fix this just remove the spaces in the jrxml file.