VO standards have enabled data centres, VO projects, and applications writers to create VO friendly tools. The key idea is that of the VO Registry, through which tools can search for data. For Euro-VO, by far the most popular tools are Aladin (images) and Topcat (tables and plotting).
A complete list of VO tools and portals is on this IVOA page. Some examples include :
Tools for image access and display : Aladin, DS9, Gaia
Tools for catalogue search, manipulation and plotting : Topcat , VOplot
Tools for spectral search and analysis : Splat, VOSpec, Specview
Web based data discovery portals : VAO portal, CDS portal , Skyview
VO friendly outreach tools : World Wide Telescope, AIDA, VAO Education site