All personnel administration tables start with PA and the infotype number behind it.
All personnel development/OM tables start with HRP and infotype (e.g. 1000) behind it.
All recruitment tables start with PB and infotype number behind it.

Transaction SE16 (data browser) is also useful.  As mentioned above, the PA infotype tables all begin with PA and are followed by the infotype number e.g. PA0001 for the Org Man infotype.

PA* – PA infotype tables
PCL* – HR clusters
PB* – recruitment tables
PCERT – payroll posting runs

Another useful table is CATSDB for CATS, and PTEX2000 for the CATS transfer table for infotype 2001/2002.

The rest of the HR Tables are as follows:
DD01L Domains
DD02L SAP tables
DD03L Table Fields
DD03T DD: Texts for fields (language dependent)
DD04L Data elements
DD04T R/3 DD: Data element texts
DD05S Foreign key fields
DD06L Pool/cluster structures
DD20L Matchcode Ids
DD24S Fields of a matchcode ID
T000  Clients
T001  Company Codes
T001E Company code-dependent address data
T001P Personnel Areas/Subareas
T012  House banks
T012K House bank accounts
T012T House bank account names
T500L Personnel Country Grouping
T500P Personnel Areas
T500T Personnel Country Groupings
T501  Employee Group
T501T Employee Group Names
T502T Marital Status Designators
T503  Employee Groups / Subgroups
T503K Employee subgroup
T503T Employee Subgroup Names
T504A Benefits – Default Values (NA)
T504B Benefit Option Texts (North America)
T504C Benefit Type (NA)
T504D Benefit Credit Group Amount
T504E Benefit Amount
T504F Benefit Costs
T508A Work Schedule Rules
T508T Texts for Employee Subgroup Groupings for Work Schedules
T510   Pay Scale Groups
T510A Pay Scale Types
T510F Assign Pay Scale > Time Unit, Currency
T510G Pay Scale Areas
T510H Payroll Constants with Regard to Time Unit
T510I Standard Working Hours
T510J Constant Valuations
T510L Levels
T510M Valuation of pay scale groups acc. to hiring date
T510N Pay Scales for Annual Salaries (NA)
T510S Time Wage Type Selection Rule
T510U Pay Scale Groups
T510Y Special Rules for Wage Type Generation
T511  Wage Types
T512R Cumulation Wage Types in Forms
T512S Texts for Cumulation Wage Types in Forms
T512T Wage Type Texts
T512W Wage Type Valuation
T512Z Permissibility of Wage Types per Infotype
T513  Jobs
T514S Table Name Texts
T514T Field Name Texts
T51D2 Wage Type Classes
T51D3 Reduction Rules
T51D4 Cumulation Rules
T527X Organizational Units
T528B Positions – Work Centers
T528C Wage Type Catalog
T528T Position Texts
T529A Personnel Event
T529F Fast Data Entry for Events
T529T Personnel Event Texts
T52BT Texts For HR Objects
T52C0 Payroll Schemas
T52C1 Payroll Schemas
T52C2 Texts for Personnel Calculation Schemas
T52C3 Texts for Personnel Calculation Schemas
T52C5 Personnel Calculation Rules
T52CC Schema Directory
T52CD Schema Directory
T52CE Directory of Personnel Calculation Rules
T52CT Text Elements
T52CX Cross References via Generated Schemas
T52D1 Valid Processing Classes
T52D2 Valid Values for Processing Classes
T52D3 Valid Evaluation Classes
T52D4 Permitted Values for Evaluation Classes
T52D5 Wage Type Groups
T52D6 Wage Type Group Texts
T52D7 Assign Wage Types to Wage Type Groups
T52D8 Valid Processing Classes – Texts
T52D9 Valid Values for Processing Classes – Texts
T530 Reasons for Events
T530E Reasons for Changes
T530F Reasons for Changes
T530L Wage Types for Special Payments
T530T Event Reason Texts
T531 Deadline Types
T531S Deadline Type Texts
T533 Leave Types
T533T Leave Type Texts
T539A Default Wage Types for Basic Pay
T539J Base Wage Type Valuation
T539R Events for Standard Wage Maintenance
T539S Wage Types for Standard Wage Maintenance
T548 Date Types
T548S Date Conversion
T548T Date Types
T548Y Date Types
T549A Payroll Areas
T549B Company Features
T549C Decision Trees for Features (Customers)
T549D Feature Directory
T549L Date modifiers
T549M Monthly Assignment: Payroll Period
T549N Period Modifiers
T549O Text for date modifier
T549P Valid Time Units for Payroll Accounting
T549Q Payroll Periods
T549R Period Parameters
T549S Payroll date types
T549T Payroll Areas
T549M Monthly Assignment: Payroll Period
T549N Period Modifiers
T549O Text for date modifier
T549P Valid Time Units for Payroll Accounting
T549Q Payroll Periods
T549R Period Parameters
T549S Payroll date types
T549T Payroll Areas
T554S Absence and Attendance Types
T554T Absence and Attendance Texts
T554V Defaults for Absence Types
T554Y Time Constraints in HR TIME
T555A Time Types
T555B Time Type Designations
T559A Working Weeks
T559B Name of Working Week
T572F Event Texts
T572G Allowed Values for Events
T572H Event Value Texts
T582A Infotypes
T582B Infotypes Which Are Created Automatically
T582S Infotype Texts
T582V Assignment of Infotypes to Views
T582W Assigns Infotype View to Primary Infotype
T582Z Control Table for PA Time Management
T584A Checking Procedures – Infotype Assignment
T588A Transaction Codes
T588B Infotype Menus
T588C Infotype Menus/Info Groups
T588D Infogroups for Events
T588J Screen Header Definition
T588M Infotype Screen Control
T588N Screen Modification for Account Assignment Block
T588O Screen Modification for Assignment Data
T588Q Screen types for fast entry
T588R Selection Reports for Fast Data Entry
T588S Screen Types for Fast Entry
T588T Menu and Infogroup Designations
T588V Business object type
T588W Event types for infotype operations
T588X Cust. composite definition of event types for IT operations
T588Z Dynamic Events
T591A Subtype Characteristics
T591B Time Constraints for Wage Types
T591S Subtype Texts
T596F HR Subroutines
T596G Cumulation wage types
T596H _Cumulation wage type texts
T596I Calculation rule for cumulation wage types
T596U Conversion Table
T599B Report Classes
T599C Report Classes
T599D Report Categories
T599F Report Classes – Select Options
T777A Building Addresses
T777T Infotypes
T777Z Infotype Time Constraints
T778T Infotypes
T778U Subtypes

Error Messages tables
T100 Messages
T100A Message IDs for T100
T100C Control of messages by the user
T100O Assignment of message to object
T100S Configurable system messages
T100T Table T100A text
T100V Assignment of messages to tables/views
T100W Assign Messages to Workflow
T100X Error Messages: Supplements