I have a variety of tools that I use:
Logos for Mac - terrific resources available but is extremely expensive. I was able to get a pretty extensive collection for it dirt cheap by picking up one of the old "Libronix" based software packages.
QuickVerse for Mac - It's ok. Resource window syncing never worked reliably for me, and the interface is a bit clunky.
eSword wrapped in Wineskin Winery - eSword continues to be my go-to Bible study software. It's interface is fast and clean, easy to search, easy to add personal notes and commentaries to individual verses, chapters, and books. When I want to focus on the Bible text itself, I prefer this over the other tools. It does require significant technical knowledge to get it running. (Wineskin Winery is basically a .ZIP file of executables that allow a Windows program to run on OSX without the need to have Windows installed)
TheWord wrapped in Wineskin Winery - Another Windows-based software that is like an expanded version of eSword.
Step Bible by Tyndale House - This is an amazing online resource, free.
http://www.stepbible.org/
ESV Study Bible online - If you have purchased the ESV Study Bible, then you should've received a card that allows you to access the online version:
http://www.esvbible.org/
What software (if any) are you currently using?