You can collect good information and tools on a payroll but personally owning a managing property creates a different stamina.  

Agency financing is a great tool for small multifamily investors.

Its about $100 and is a fantastic and easy to use tool to capture what you're doing on the screen and then edit it.I also highly recommend Vincent Laforet's blog.

I had a good experience with erentpayment.com, but you should also check out sparkrent.com, which offers similar tools and direct deposit, but only costs $1/month vs $3/month.

For instance House A has a basement, House B doesn't - are their any technical tools, or regional guides to what the lack of that basement means for the relevant price adjustment to the comp or subject? 

Buildium just bought All Property Management, a lead generation site that we use and like, they are working on some integration tools with CRM and lead maintenance.  

@Neil G.I've used http://www.idxbroker.com/ in the past and it comes to about $30-$75 a month, depending on what additional tools and services you subscribe to.Personally, we're starting to look at not including the IDX integration directly into the site and just linking folks to a page with the search widget provided by themls.com, included with you MLS subscription.

If you're willing to get down into the weeds and learn just a bit on the way, all the tools Google gives you makes it hard to beat Google Sites IMO.The interface isn't nearly as intuitive as Squarespace, but I'd say its at least as easy as Wix and you can do much more.

I spent a few bucks at the hardware store on some cheapo tools and the least expensive products I could find.

 @Bill Gulley  I had some interest in learning lease options to have that tool in the bag if the right situation presented itself but I've been unable to figure out all the details to make it legal.