VFR aircraft collisions are pretty rare. There are some really good things out there in terms of improving lookout and actually spotting other traffic. Conditions can make a big difference but gadgets are unlikely to help. With over half of the present registered aircraft being unlikely to have transponders then the gadget is probably not the answer.
Work on your lookout - it is amazing how much you can improve it by concentrating on a good scan, working at focusing from near to far and looking for very small targets. I rarely fly in straight lines, avoid obvious honey pots and make of a point of trying to visualise where other traffic on the frequency is. I've still been surprised - but thankfully never that close.
Even if we all end up with Mode S boxes there will still need to be some other system, aircraft TCAS or ground collision warning - technology is unlikely to fix the problem.