I've decided to open-source an old and rusty project called Actihunt that sits there for more than 3 years.
Check it out @ www.actihunt.com
The project does one thing and one thing only, it synchronizes activities between Runkeeper and Strava, this is all, and it did its job pretty well in all this time.
Activities index page
It shows activities listing for the selected provider where you can ‘Sync’ or view activity details by clicking on ‘Show’, see below.
Activity details page
Nothing fancy here, just a few activity details.
And finally the account page, with name/email/timezone and connected providers.