http://treasurechest.i2p/connect.html
Otherwise, you can use its HTTP proxy, provided it supports the CONNECT method (I think both daemons do, and they both listen at port 4444 by default). FileZilla supports both kinds of proxies (look under 'generic proxy' in the global settings). If you do use FileZilla or some other multi-protocol client, be sure to add 'sftp://' before the host name or manually select the SFTP protocol.