It contains more than 100 functions and procedures, some documented and some not. You can always read the source (and most of them are trivial to understand).
 
Fully functional
Source: Included

• Hook technology supports Windows XP 32-bit SP2 and up (including WoW64 x64 support for 32-bit processes)
• Ultra-tiny memory footprint which is exponentially smaller than similar, less-stable commercial hooking packages
• Hybrid Hook uses the "code overwriting/rewriting" hook method internally. This is also the method that Microsoft's Detours hooking package uses which is more reliable and overall better than combinatorial IAT/EAT hooks.
• No disassembler "hacks" are required to "guess" at CPU instructions executed at run-time due to sophisticated internal logic/intrinsics, hence the name "Hybrid" Hook
• Fully thread-safe code hooking.unhooking which uses atomic operations and thread memory access barriers backed by CPU mechanisms to ensure synchronization and stability
• Hook code or exported APIs in any module with ease, all complexity is removed for the programmer.
• Easily allows you to call the original API after hook installation without needing to "unhook" in order to do so
• Tested to insane extremes against the most popular hooking SDKs available to the public
• Process unintrusive low-level DLL injection supported which extends the Windows kernel32.dll.CreateProcessA() API. No spawning of threads is needed in the target process to load DLLs, no CPU registers are tampered with inside thread contexts etc. Support for code injection into already running processes is included as well, utilizing the same principle
• Process and thread identifier conversion helper functions are also included in Hybrid Hook which allow for process handle and thread handles to be converted to their respective identifiers
• 2 main hook flags are supported for hooking code atomically which keeps multiple threads from experiencing race conditions as well as accomplishing multi-processor safety. A flag for hook callback synchronization during unhooking of code is included which is an "extra" safety mechanism.
• Extra stable unhooking is realized through the flag (SYNC_UNHOOK) which explicitly relies on 2 available functions __EnterHook() and __ExitHook() respectively. See the Hybrid Hook SDK notes and demos for more information on this.
• An API for returning the caller module handle (HMODULE) exists and is especially useful within the context of a hook's callback function, it essentially allows for one to modify an API's behavior based on the caller if they choose to
• IsSystemProcess() API is available to determine if the calling process is SYSTEM owned which is sometimes imperative to know while doing code injection work

Managed VCL can:

• Create .Net objects from assemblies not registered for COM, using assembly name or location, and loading .Net assemblies from streams;
• Create and use .Net objects that are not COM visible;
• Create .Net objects using parametrized constructors;
• Call properties/methods/fields of .Net object including static properties/ methods/ fields;
• Handle .Net exceptions and get all .Net exception properties including exception type name, StackTrace etc.;
• Get information about loaded instance of .Net framework such as memory usage and size of heap by generation;
• Load needed .Net runtime and even select which version of runtime to use on startup;
• Place .Net controls on VCL Win32 form;
• Use ADO.Net datasources as TDataSet descendants in Win32 applications. ADO.Net will be native and most supported API for SQL Server 2005 (Yukon);
• Host ASP.Net pages and services;
• Embed .Net assemblies into Win32 application as resources;
• JScript.Net - lets you execute JScript.Net scripts from Delphi/ C++ Builder application;
• ASP.Net - process ASP.Net pages and services from Win32 applications;
• More...

• Over 70 emulated functions are available and extremely simple to call
• All major "Power" thread and process APIs are emulated which include Native APIs, Kernel32 APIs and PSAPI
• Increased security and reliability. Symbiote's emulated functions do not internally use any Win32 API, instead each emulated function speaks directly to the kernel by way of inline assembly code logic so even in the event that a given Win32 equivalent API is hooked, the emulated function's result would not be tampered with or jeopardized in any way giving your code unparalleled integrity which you can trust.
• Overall executable size increases by only 4kb when you include Symbiote into your projects
• Many powerful custom functions are implemented which make your jobs much easier. These functions that were customly written were never offered by Windows or exposed through any "Official" API but should have been all along.
• Undocumented functionality. Symbiote uses many internal process and thread structures as well as other "secrets" in order to offer the most powerful emulation functions available anywhere. Symbiote takes all the complexity out of such low-level undocumented concepts so you do not have to relearn anything, just continue calling funtions in the Windows environment as you normally would.
• Symbiote can be fully implemented with little to no code changes to your existing projects. Emulated functions are all named identically to their Win32 API counterparts with the exception of an appended suffix "LL" which stands for Low-Level. i.e: Win32 function ReadProcessMemory() would translate to the same function in Symbiote as ReadProcessMemoryLL()
• Simplified function calling. All emulated functions keep the same Win32 function base name, parameter types and counts as well as calling convention so calling these functions are no harder than calling the Win32 function.
• No additional file dependencies. All the process and thread power of the Process Status API helper library (PSAPI), kernel32.dll and ntdll.dll are wrapped into one self-contained unit so you will not need to rely on any external process libraries ever again.
• Symbiote is completely compatible with the following 32-bit operating systems, including any variants (Home, Pro etc.) Windows 2000, Windows XP/MCE, Windows Server 2003, Windows Vista.
• Symbiote has been incorporated into public anti-rootkit programs (even my own anti-rootkit security project "kX-Ray"), process listing tools (similar to Process Explorer from SysInternals), code profiling tools, API Hook libraries, PE protection schemes (i.e> schemes similar to TheMida, EXECryptor etc.) and many other powerful projects.
• Updates are completely FREE to existing customers. Yes, even source code updates.