What benefit or incentive is there for someone to run their own ripple client or ripple server? What incentive is there for someone to run their own Ripple client/server in order to make it an actual decentralized system? With Bitcoin, you can mine to generate new bitcoins and collect transaction fees. Is there a Ripple equivalent?
There is no mining in Ripple. The incentive to run a client is to use the Ripple network. There are several incentives to running a server. The main one, as Lohoris suggested, is to support the network. This is the same reason Bitcoin nodes relay transactions.

From the wiki:


Anyone whose business relies on the network:
    Gateways
    Merchants
    Arbitragers
    Day traders 
Anyone who wants to support currency choice:
    Digital rights groups
    Libertarian groups
    Individuals 
Anyone who wants to support the underbanked:
    Organizations
    Individuals 
Anyone who wants to provide a public service:
    Universities
    Anyone who provides hosting services for open source projects 



As a high-volume merchant or arbitrager, running a node is the most efficient and reliable way to participate in the network. If nodes feel you aren't pulling your weight, they can either disconnect you or impose a proof of work requirement on you to remain connected to them. This is because legitimate high-volume queries are indistinguishable from abuse. As a fully-participating node, you can see transactions before they're voted into consensus sets.