In order for each of them to view your site properly; without having to swipe around to find hidden sidebars, or zoom in and out to see the whole page properly, you need to use what they called Responsive themes for your sites.
This kind of theme will automatically resize and realign your site to suit the size of the screen of their tablets or smartphones accordingly they viewed on.
1. Montezuma
http://test.bytesforall.com/
2. Constellation
http://constellationtheme.com/
3. Responsive
http://themeid.com/responsive-theme/
4. SimpleX 2.0
http://www.wpshoppe.com/themes/simpleX/
5.Ari
http://ari.elmastudio.de/
6.Landscape WordPress Theme
http://landscape.blankthemes.com/
7.Designfolio
http://www.presscoders.com/designfolio/
8. Skirmish
http://skirmish.blankthemes.com/
9. WP StrapSlider Lite
http://www.wpstrapcode.com/wpstrapsliderlite/
10. Mosaic
http://wildweblab.com/theme/mosaic
11. Simple Grid
http://www.dessign.net/simple-grid-theme-responsive/
12. Unique
http://www.dessign.net/unique-theme-responsive/
13. Esplanade
http://www.onedesigns.com/wordpress-themes/esplanade-free-wordpress-theme
14. Gridly
http://www.eleventhemes.com/gridly-theme/
15. Minimalizine WordPress Theme
http://hirizh.name/minimalizine-wordpress-theme/
16. TumblePress
http://colorlabsproject.com/themes/tumblepress/
17. Response
http://cyberchimps.com/response/
18. Neuro
http://wordpress.org/extend/themes/neuro
19. Orion
http://www.web2feel.com/orion/
20. Live Wire
http://themehybrid.com/themes/live-wire
21. Twenty Ten
http://responsivetwentyten.com/
22. iFeature4
http://cyberchimps.com/ifeature-free/
23. Eclipse
http://cyberchimps.com/eclipse/
24. Cakifo
http://jayj.dk/cakifo-free-wordpress-theme/
25. Fanwood
http://devpress.com/themes/fanwood/
26. SimpleMarket
http://premium.wpmudev.org/project/simplemarket/
27.320 and up
http://stuffandnonsense.co.uk/projects/320andup/
28.BonPress
http://www.wpzoom.com/themes/bonpress/
29.Yoko
http://www.elmastudio.de/wordpress-themes/yoko/
30. Sunspot
http://theme.wordpress.com/themes/sunspot/
31. Buttercream
http://carolinethemes.com/2012/03/13/buttercream/
32.DailyPost PRO
http://wplook.com/dailypost
33. Adapt
http://www.wpexplorer.com/adapt-free-responsive-wordpress-theme/
34. iTheme2
http://themify.me/themes/itheme2
35. Yasmin
http://www.web2feel.com/yasmin/
36. Bones
http://themble.com/bones/
37. Clean Retina
http://www.themehorse.com/themes/clean-retina/