There will never be enough ways to search through Craigslist.
To help in the hunt, there's a new tool called Search All Craig's Lists that does the dirty work for you--scouring all the cities and countries with local Craigslists and compiling them into one index that can be searched extensively, and with ease.
It uses Google custom search, which is fast but not as precise as using Craigslist's own search tool. You can narrow down what area of the country you're in, but that's only so helpful. In my search for the video game Call of Duty 4, I got results from Seattle all the way to Reno. Knowing Google search parameters helps narrow it down even further, but it's not nearly as simple Craigslist's, which let you narrow it down by neighborhood.
Where sites like this come in handy is when it comes time to find obscure items. Something like a stamp or coin collection might be something somebody is willing to ship, whereas most goods on the service are for in-person pickups only. They can also be helpful in case you're trying to track down stolen items, especially where you're not sure how far the thief has taken your goods, which in my own personal experience was not that far. A service like this would have helped me dig through the results that much faster.
Another service that does this is Crazedlist, which keeps you inside the confines of Craigslist's search engine, and shows all of the results from all of the various cities in the same window. However the "hack" Crazedlist uses requires toggling a certain setting on your browser, which many folks may not be comfortable with.