Many DD-WRT functions are designed for using the router as a public-access hotspot. If you're setting up one of these in a business or residence, it's handy to have them in the box and not need to put them together by hand.
- Client isolation. Wireless clients can see only the access point and not each other -- quite important if you want multiple people to share the same access point and not get into each other's shared files.
- Sputnik Agent. An add-on that allows an access point manager to use the SputnikNet remote-management system for controlling multiple access points from a single Web-based console. SputnikNet has both free and for-pay management tiers, depending on your needs.
- Hotspot System. This appropriately named service lets you manage multiple locations, as well as the billing of clients who connect to your hotspot.
- Wifidog. Another access-point portal solution, Wifidog provides a broad range of options from simply displaying a splash page for users (for no-strings-attached access) to requiring actual purchase of access time.
- ChilliSpot. Yet another open source access controller for hotspots, ChilliSpot uses RADIUS authentication. Note that ChilliSpot is a legacy project that is no longer actively maintained, but is included with many DD-WRT builds as a backward-compatibility measure.
Some things are not included in every build of DD-WRT. OpenVPN, for instance, is limited to just a few builds. If you're using virtual private networks to connect to remote servers, you'll want one of the DD-WRT builds that includes OpenVPN, which lets you make VPN connections without needing client software on the PC connected to the router.
Finally, DD-WRT includes extensions to allow the truly adventurous to do things with their router that the manufacturer never intended -- adding external USB connectors or aftermarket memory card readers, for instance. Though beyond the realm of most ordinary users, they open up fascinating possibilities for the hard-core hacker.