KernelEx is an Open Source compatibility layer with an aim to allow running Windows 2000/XP-only applications on Microsoft Windows 98 and Microsoft Windows Millennium operating systems.

Reddit - r/windows98
Reddit - [GUIDE] Can I run Windows 98/Me?

MSFN - Pinned Topics regarding 9x/ME:

• MSFN - Compatible Hardware with Windows 9x
• MSFN - Last Versions of Software for Windows 98SE
• MSFN - Day-to-day running Win 9x/ME with more than 1 GiB RAM

MSFN - Win98 driver for ATI X800/X850

the memorial homepage of R. Loew Electronics Consulting
Dedicated to the works and memory of Rudolph R. Loew (rloew)
philscomputerlab.com - Rudolph R. Loew (rloew) archive of patches
Vogons - Rudolph Loew apparently passed away in September 2019

Compdigitec Labs - Sound in Windows 98 on VMware
VMware Workstation 5.5 - Windows 95 and Windows 98 Guest Operating System Performance Tips

YouTube - Windows 98 20th Anniversary All New PC Build by Tech Tangents.
Upgrades for The New Windows 98 PC by Tech Tangents.

Grystmill.com home of the following:

• CD_1: Windows Updates Security Updates 2004 (SECUP_9x.iso)
• CD_2: Unofficial Updates for Win98, 98SE and ME (UPDATE9x.iso)

MDGx
MDGx - Windows 98, 98 SP1, 98 SE + ME - Updates, Patches + (Hot)Fixes

GitHub - JHRobotics/patcher9x Patch for Windows 9x to fix CPU issues.
Windows 9x TLB Invalidation Bug

LoneCrusader:

• FIX95CPU - Allows Windows 95 to run on processors faster than 2.1GHz.
• XUSBSUPP - Combines all official Microsoft USB updates for Windows 95 OSR2.
• Unofficial Intel Chipset INF Files - An unofficial set of INF files supporting newer Intel chipsets. Designed to be “slipstreamable” and extend original Windows 98SE files.

HPC:factor - Windows 98 Patches & Updates Guide

Win98 4GB RAM patch via Major new development in Windows 98 RAM memory capability patch has been discovered!
stackexchange - Windows 98 with 2GB of RAM

VBEMP 9x Project Universal VESA/VBE Video Display Driver (for Windows 9x Architecture) free for noncommercial use only

• Supports ALL of MS Windows 9x Family (Windows 95, Windows 98, Windows 98SE, Windows Me)
• supports a wide range of videocards emulated via virtualization software: Bochs, QEMU, VMware, Innotek VirtualBox, Microsoft VirtualPC.

Philscomputerlab.com - Windows 98 USB Storage Driver

SourceForge - HimemX

IndirectSound emulates audio hardware acceleration on modern Windows operating systems. This enables older games to have 3D positional audio (i.e. surround sound played out of rear and side speakers) like they were intended to when they were originally released.