With FusionCharts, you can even have charts that scroll thus not compromising on the amount of data displayed along the x axis nor the look and feel. There are so may properties that can be set for the chart too. And I think with this you can set a lot of values dynamically like dynamic trend line values. Really cool. But I think the drill through functionality might be a little lacking when we try using this through Cognos. FusionCharts does have a linked report concept that I am hoping is similar to drill through functionality but need to check it out.
PaulM's contribution:
The drill through (clickURL) functionality works perfectly. You can even perform a self drill through to mimic a drilldown.
The trick is to use repeaters not repeater tables or lists with HTML items. Lists and repeater tables insert useless table and cell tags. Text items are wrapped in spans.
There are two ways of embedding the data directly into the graph.
1. You can use the setDataXML() function.
2. You can also use the HTML embedding method detailed here: http://www.fusioncharts.com/docs/FirstChart/HtmlEmbed.html