Direct Connect allows you to share files over the Internet without restrictions or limits. The client is completely free of advertisements and has a nice, easy to use interface. Firewall and router support is integrated and it is easy and convenient to use functionality like multi-hub connections, auto-connections and resuming of downloads.
LDC is a client for Direct Connect network. It takes a lot of features of many other clients. Since DC is developed under GNU/GPL, you can download source and modify it.