It is important to tie your technology to your objective because technology is not the end goal the content is. Technology should be used as a means for them to learn the content of your classroom and is not itself the learning goal. If you do not keep the technology congruent, you may end up with many tech savvy student in your chemistry classroom that know nothing about chemistry.
Most likely your goal at having stations in your classroom is for students to discover, learn or practice something. Since you cannot be at all places at once it is important that students are held accountable. This can be as simple as writing a sentence about what they learned or contributing to an online discussion through a back channel like Today's Meet. Your goal of holding them accountable should be that you are gaining some type of formative assessment. Something that tells you as the teacher what they have gained from the station and where you should go next in the classroom-- either moving forward or filling in the gaps or answering questions student's posed.
I really like the PhET simulation and already use several in my classroom. They are great to use in chemistry because they help students visualize concepts that happen at the atomic level and cannot be seen. These simulations can be used at a station where they can manipulate the simulation and then answer some follow up problems to check for their understanding or have them describe their learning of the concept.
I also liked learning about the SBISD interactive database. Obviously, this is not a place to send students but I can go back throughout the year as a teacher and discover more useful website for my students. I can see this being very beneficial because it is hard to store all of the Web 2.0 tools available in my brain. I am glad to know there is a helpful resource for me.
I am struggling to find very many Chemistry specific apps. There are a couple formula writing apps out there they can be good for student practice. That is an easy station for when students need repetitive practice. Also, there interactive Periodic Table apps they I will definitely download because students always need access to the Periodic Table to reference while working problems.
Another app that maybe useful is the Whiteboard Free app. I could see students illustrating a chemical bond or a molecular picture and being able to share it with me an other students. In chemistry, drawings and models can be very important to help assess student understanding of a concept.
I am still exploring uses of iPads in my classroom, but I am challenging myself to make them an useful and integral part of my room. I can see them being video recorders, communication devices and more.