You can find some great Information at the link below, for many of the WRT54GL + more firmware
LinkSys Info Firmware Forum
OpenWrt is described as a Linux distribution for embedded devices.
Instead of trying to create a single, static firmware, OpenWrt provides a fully writable filesystem with package management. This frees you from the application selection and configuration provided by the vendor and allows you to customize the device through the use of packages to suit any application. For developer, OpenWrt is the framework to build an application without having to build a complete firmware around it; for users this means the ability for full customization, to use the device in ways never envisioned.
Gargoyle is an interface for small, widely available routers such as the Linksys WRT54G series and the La Fonera. It provides functionality above and beyond what the default software provides including sophisticated dynamic DNS, quality of service, and bandwidth monitoring tools.
The primary goal is to provide a polished interface for these advanced tools that is at least as easy to configure as any existing firmware. Gargoyle is based on top of the most recent Kamikaze release of the OpenWrt firmware, but unlike other Web interfaces for OpenWrt it places a strong focus an usability and is meant for average users, not just power users.
DD-WRT is simply a project which was originally based on the official GPL Sources of Sveasoft Alchemy. but turned later to a OpenWRT Kernel vase firmware variant. Due the nature of GPL based projects, this firmware will be also release under this license. Initially i wrote this modification to make it possible, to use the Linksys WRT54G/GS inside our Wireless Lan network as cheap replacement for our professional Lancom and Orinocco access points. so what was missing? first, we are using radius authentication with a central account management inside our network for user authentication. There is already a radius application available for OpenWRT, but openwrt was no choice since it is not user friendly for a non computer professional without any linux knowledge. so i just integrated it with some small enhancements in the alchemy software. my wrt-radauth modifications:
radius server timeouts will not be a problem anymore. a client is authenticated just up to the point, the server says really 'no'. a connection timeout will not have any influence to this workflow.
additionally i found it really helpfull to use a external filesystem device inside the WRT. my choice was a samba client since it is useable on any computer platform. you can easilly mount a windows network share into the wrt and additionally its also possible to start a script after mounting from this device. but the work was not over. also if currently the server/client watch function is still under development, i already implemented the RFlow traffic monitoring and management tool into the web interface. this tool is already inside DD-WRT, but you have to start it manually and so far it looks unfinished. (daemon mode does not work). so i finished it and yes now its working inside my DD-WRT and you can configure it out from the administration window.
"Tomato is a small, lean and simple replacement firmware for Linksys' WRT54G/GL/GS, Buffalo WHR-G54S/WHR-HP-G54 and other Broadcom-based routers. It features a new easy to use GUI, a new bandwidth usage monitor, more advanced QOS and access restrictions, enables new wireless features such as WDS and wireless client modes, raises the limits on maximum connections for P2P, allows you to run your custom scripts or telnet/ssh in and do all sorts of things like re-program the SES/AOSS button, adds wireless site survey to see your wifi neighbors, and more."
"Routers that are known to work with Tomato:
* Linksys WRT54G v1-v4, WRT54GS v1-v4, WRT54GL v1.x, WRTSL54GS (no USB support)
* Buffalo WHR-G54S, WHR-HP-G54, WZR-G54, WBR2-G54, WBR-G54, WZR-HP-G54, WZR-RS-G54, WZR-RS-G54HP, WVR-G54-NF, WHR2-A54-G54, WHR3-AG54
* Asus WL500G Premium (no USB support), WL500GE
* Sparklan WX6615GT, Fuji RT390W, Microsoft MN-700
Note: This will not work on Linksys WRT54G/GS v5 or newer WRT54G/GS routers."
FreeWRT is a meta GNU/Linux distribution for embedded systems. In this context "meta" means, you can build the complete distribution from source. FreeWRT is meant to be an appliance development kit (ADK) especially designed for embedded system developers and advanced users.
Tarifa is a replacement firmware for the Linksys WRT54GL gateway/router. It adds a list of features, solves bugs and increases range and speed. Installing is as easy as the original firmware, you can flash (and flash it back) via the web interface.
For P2P it raises the limit of maximum simultanious connections, the hash table size is set from 128 to 3079, increasing the SPI-firewall speed with at least 10%. The Linux 2.4.20 kernel is patched with CAN-2003-187, preventing Netfilter to fail to identify connections with an UNCONFIRMED status and causes large timeouts. All default tcp time-out values are set between 2 to 4 minutes.
Linksys original firmware comes with Netfilter/iptables 1.2.7., this is very old and buggy. A new UPnP gateway service came, named miniUPnP, this makes it possible to fully use the new iptables code. The new miniUPnP code is released in Tarifa b030.
The main feature of the router is the wireless interface to connect to wireless clients. Tarifa firmware increases the wireless range, by raising the transmit power. An external antenna can also be connected and selected by the firmware. For larger networks routers can be added and linked wirelessly by the WDS system.
X-Wrt is a set of packages and patches to enhance the end user experience of OpenWrt. It is NOT a fork of OpenWrt. We work in conjunction with the OpenWrt developers to extend OpenWrt.
Our packages currently work with the latest public release of OpenWrt - Kamikaze 7.09. Support of OpenWrt's upcoming Kamikaze firmware is coming soon. We currently have a stable webif for OpenWrt White Russian. Explore this page to learn about our work, or just skip straight to installing X-Wrt and see the fruits of our labor yourself.