I have settled on using Runkeeper while running as I like the fact it tells you timings every 5 mins. Then after uploading them I am transferring them to Sports Tracker as I feel it shows the information much better
There's Sports Tracker which will give you a graph showing your speed against distance. Alternatively if you can access the phone you could try somehow (I don't know how) to make each run interval a lap and each walk period a lap? I know how to do this on my watch but not my phone!
These are set up to deal with laps rather than intervals
Looks like this could be what im after. Will try it tonight