One of the open source community's greatest strengths is its willingness to create and contribute to a project. And when a project just isn't offering what they like, you are likely to find them starting up their own ventures.
Tomato is this writer's favorite. Suffice it to say, however, there are plenty of other open source firmware choices available, each putting their own spin on things.
DD-WRT is, by far, the most popular firmware you are likely to run into. The developers behind it have put together a robust set of features and support for a large number of routers, which gives it the largest following and plenty of willing guinea pigs that test their releases. That being said, it's also one of the most stable projects available given the number of active participants during its testing and development.
If you're looking for that all-purpose, Swiss Army knife firmware your best bet is to focus on DD-WRT.
Depending on your router's total RAM and flash memory storage, you may end up stuck with a slimmed down version that doesn't offer all of the features you were interested in. You still get improved stability and a more responsive router with even the lightest version.
It offers features such as Chillispot, which allows you to run a Wi-Fi Hot Spot environment that allows for web-based authentication for access to your network. If you're more of the telecommuting type, you'll be interested in the OpenVPN support offered by the VPN and Mega branches of the firmware. It creates a secure connection between remote computers, useful when you don't want your important work to end up compromised.
If you're looking for that all-purpose, Swiss Army knife firmware your best bet is to focus on DD-WRT. Its immense feature set covers all the bases and it is user-friendly enough to set up properly. If it doesn't prove friendly enough for you, there's extensive documentation and plenty of support to be found on their forums.
Freifunk is a prime example of a purpose-built firmware. Ignoring all of the fancy features found in other projects, it instead aims to be a solution for rolling out your very own mesh network using run of the mill routers.
While not a solution for the home and most small businesses, mesh networks (with enough units) can provide a wide area of wireless coverage with automatic path recovery should a unit in the area fail to respond. A reliable option, if a logistics nightmare to set up, so you'll be need your thinking cap and quite a few friends if you're planning on tackling a mesh setup.
If all-out security is on your mind then PacketProtector is one project for you. Its full suite of features requires some of the more powerful routers available, but in return, it can take on some of the most malicious threats the Internet has to offer.
They start with content filtering to keep unwanted content from reaching any connected PC, perfect for that productivity boost that occurs when you aren't allowed browse blocked websites. Anti-phishing help comes in the form of OpenDNS, which runs its own community supported and reviewed anti-phishing site list, so a good bulk of information-thieving sites are blocked from the outset.
The most interesting feature of all may be its ClamAV anti-virus support. While its speed and accuracy is beyond the scope of this article, the concept of having your router handle anti-virus scanning duty is a compelling one and could save some precious CPU cycles, not to mention eliminate the hassle of maintaining proper AV software on your systems.
For now, the project screams "beta" as far as some of its features go, but it will surely get it quite a bit of attention as beefier routers are launched—if they can extend their support to them, that is. In all, PackerProtector is an intriguing option for the safety conscious out there.
This was a brief look at a few of your options, should you be adventurous enough to try out a new firmware on that consumer-level router you snapped up. There are risks involved, and all sorts of warranties are bound to be voided, but the benefits usually outweigh the risks and the features and improved performance and stability are hard to pass up.