Last week someone had ask me for some tools and good resources for helping him with his old sharepoint projects that were not yet migrated.
I had send him back the list of resources i8 had been using and some developments where i had collaborate. So here it goes some of the best references for you to use on your projects. Some of them are also a good choice when used in Sharepoint 2013
SPSite Lokup
-> http://sp2010filteredlookup.codeplex.com/
Multiple providers Authenticattion
->http://spautomaticsignin.codeplex.com/
->http://sp2010fba.codeplex.com/
sharepoint search xslt configurations
->http://sharepoint2010search.codeplex.com/
sandboxes
->http://sandbox.codeplex.com/
Taxonomie deploys
->http://termsetimporter.codeplex.com/
development frameworks
->http://spgenesis.codeplex.com/
developer dashboard
->http://devdashvis.codeplex.com/
start and stop Sharepoint
->http://sharepointserviceman.codeplex.com/
Google analytics integration Sharepoint
->http://spgoogleanalytics.codeplex.com/
Newsletter Generator
->http://spmailing.codeplex.com/
sharepoitn factory
Tools for kick solutions satartup
http://spc3.codeplex.com/
I hope this information can be so useful for you, as it had been for me in the last years