In an attempt to get Google to index our content in a more efficient manner I've removed our category pages and created an old-school-style crawlable sitemap at the bottom of every page. I've found that programmatically assigning products into categories is quite hard to get 100% accurate and using our item search feature is a much more efficient way of finding items rather than browsing the 26,000 categories I used.
Well, it's been a long time in development but I've finally managed to get the system to a point where I feel it's usable and genuinely helpful for the end-users. I've now pushed the website live and I'm just waiting for Google to index all the product pages. 15,000 still waiting. I've still got a huge amount of work to do while balancing this all out with my demanding 9-5 but I'm slowly getting there and it's a good feeling making a software system that actually helps people and good causes.