I don't think the Ripple guys promote these features as much between individual users because Ripple is focused on financial institutions, but the underlying mechanics with trustlines are the same for users, gateways & market maker institutions. Ripple's pathfinding algorithm seems very useful.
Gateways
A gateway is any person or organization that enables users to put money into and take money out of Ripple's liquidity pool. A gateway accepts currency deposits from users and issues balances into Ripple's distributed ledger. Furthermore, gateways redeem ledger balances against the deposits they hold when currency is withdrawn. In practice, gateways are similar to banks, yet they share one global ledger known as the Ripple protocol. Depending on the type and degree of interaction a user has with a gateway, the gateway may have anti-money laundering (AML) or know your customer (KYC) policies requiring verification of identification, address, nationality, etc. to prevent criminal activity. Popular gateways as of 2015 included Coinex, Ripple Fox, Panama Bitcoins, Payroutes, Ripple Union, Gold Bullion International, Bluzelle, Bitstamp, SnapSwap, and btc2ripple.
Trustlines and rippling
Pictured is the 2014 Ripple user interface that allows for advanced users to add trustlines and "rippling."
Users must ‘extend trust’ to the Ripple gateway that holds their deposit. This manual creation of a trustline indicates to the Ripple network that the user is comfortable with the gateway’s counterparty risk. Furthermore, the user must put a quantitative limit on this trust and create a similar limit for each currency on deposit at that gateway. For example, if a user deposits US$50 and BTC2.00 at The Rock Trading, the user will have to grant trust of at least that much in both currencies to the gateway for the monies to be available in the Ripple network. When a user has allowed multiple gateways in the same currency, there is an advanced option to allow "rippling," which subjects the user’s balance of that currency to switch (or ripple) between gateways. Though their total balance doesn't alter, users earn a small transit fee for providing inter-gateway liquidity.
https://en.wikipedia.org/wiki/Ripple_(payment_protocol)
Understanding Trust Lines
https://ripple.com/knowledge_center/understanding-connecting-to-a-gateway-trust-lines-2/Using Ripple for Cross-Currency Payments (mentions path finding)
https://ripple.com/knowledge_center/using-ripple-for-cross-currency-payments/Here is David Schwartz's explanation of the pathfinding algorithm:
https://forum.ripple.com/viewtopic.php?f=2&t=6094#p43645"This process includes looking at which order books, accounts, and ripple lines exist and are authorized to carry the payment. This finds a set of candidate paths that are then filtered."...
Hope this helps...
BTW Being able to use P2P credit trustlines & Local Exchange Trading System(LETs) in a web of trust was the main reason I followed Ripple for a long time.