I found the list here:
http://www.sflow.org/products/collectors.php
But was wondering if there are open source projects like Zenoss or others that can do SFlow collection and reporting for more than a 24 hour time period?
I did see that Zenoss has partnered with someone for a free one and will test that one out but wondered if there were any others out there that had some decent graphical views and maps and weren't impossible to setup.
I've actually been looking at the same type of setup. InMon's sflow toolkit seems to be the choice right now. Unfortunately their download site has been broken all day for me :(. Their tool sflowtool can resend the sflow's as normal netflows. So you could use that to dump it into any of the many very good netflow analyzers.
My personal goal was to get this working to redistribute to netflow-tools so i could use the flowview Cacti Plugin.
If InMon's download site starts working next week i'll let you know how i made out.
ntop also supposedly is able to handle sflows, but i wasn't able to get that working right.
Have you tried using nfdump/nfsen? I have used nfdump/nfsen for netflow v5/v9 and they work without a glitch, really powerful set of tools. I personally have not used them with sflow but I know that there is an option to compile nfdump with sflow support.
Plixer has a product called Scrutinizer that reverts to a free version after its 30 day trial is over; it's useful for some reporting but is focused on environments with many sFlow devices (it wasn't as useful as nTop in my environment with just 1 core switch exporting flows).