The University of Alabama School of Law
You can find decisions published by various Alabama state agencies on Westlaw within Alabama State Materials under Administrative Decisions & Guidamce. Coverage will vary depending on the agency, however, Westlaw provides access to decisions or orders from the following agencies: the Attorney General of Alabama; Alabama Department of Environmental Management; Alabama Securities Commission; and Alabama Department of Revenue. You can easily find the 10 most recent decisions/orders for each option listed below and, if you want to see Westlaw's entire collection, you can use the search bar at the top of the page.
You can find formal opinion letters that were prepared by the Attorney General's Office
Alabama Administrative Materials can be found on Lexis under All Alabama Administrative Materials in the Alabama state materials. You can find all administrative materials and agency decisions pertaining to Alabama state agencies and the Alabama Attorney General's Office that are available on Lexis.
You can find Alabama administrative materials on Bloomberg Law by searching Alabama Rulemaking in the general search bar or going to the Popular Links section and selecting All Legal Content. From there, make sure to change the source content type to Select Sources by U.S. Jurisdiction, then State Law, then Alabama, and Alabama Regulatory & Administrative. You can find proposed, final, emergency, temmporary and interim rules, as well as regulatory notices. Unlike other sources, the information on Bloomberg is organized by date of the rulemaking action.

Individual agencies are often an excellent source for news, regulations, hearings/administrative decisions, and other background information, though the quality or usefulness of the information often varies by agency. For a list of each agency with links to their websites, please check this page. You can also check out GODORT's (American Library Association Government Documents Round Table) page on Alabama State Agency Databases. They include links to Alabama State Agencies listed by database subject.
Alabama Law Office Practice Deskbook by Robert L. McCurley, Jr.