CeroWrt provides polipo, which is a caching web proxy server.
Proxying is an integral component of the HTTP architecture, commonly used in institutional environments behind firewalls but seldom used in home environments, despite easy to configure automatic mechanisms for configuration (WPAD and PAC), and nearly universal support in all modern equipment and browsers. Due to the lossy nature of wireless, proxying theoretically has native advantages - each proxied connection consists of two (or more) 'split TCP' streams, which can ramp up and down independently of packet loss - smoothing out bandwidth on both sides of the bottleneck to the Internet.
As presently configured in CeroWrt, a polipo'd connection competes poorly with non-proxied streams, in general only being a win where it has local cache and/or can convert connections into using HTTP/1.1 pipelining. The router defaults to TCP Westwood+ which attempts to be bandwidth friendly, and most clients use a TCP that is more aggressive, so proxied connections can end up starved for bandwidth vs. direct connections.
There are multiple solutions to this problem - making your web clients use the proxy is probably the best of them, which leverages the advantages of Westwood+ for wireless. Another option is to enable TCP cubic on the router (not recommended, except for testing), and a third, to apply a different level of QoS to proxied streams than non-proxied, which is the approach being followed by the ongoing DiffServ work elsewhere.
It is reasonably effective to merely put your highest bandwidth streams (e.g. video) through the proxy. As these devices tend not to move, you'll only have to configure them once, in order to gain the benefits of proxying elsewhere on your network.
The GUI for polipo is reasonably complete. All you need to do to turn it on via the GUI is allow in your private networks (including IPv6!), and if you attach a USB stick as a local cache, point it at the location you plan to be caching in, then configure your devices to access it on port 8123. While enabling automatic wpad and proxy.pac configuration is feasible with the integral web server there are security implications we have not yet addressed. (please see the wiki for updates)
An ad-blocking and experimental web proxy, 'privoxy', is also in the package repository for CeroWrt. It works well to provide ad blocking facilities to devices lacking them, particularly of use in bandwidth scarce locations such as the developing world.
Polipo can act as an effective IPv6 to IPv4 translator. You can enable your browser to run the proxy over IPv6 and nearly eliminate your usage of IPv4 for most operations.