I'm an avid user of the Aldiko eBook reader app and recently got myself a tablet. Naturally, I wanted to be able to read my books on my phone and the tablet. I hoped there would be something that would allow me to easily do this, but I only found a stale thread on the Aldiko support site that said they would support this feature sometime in the future. 
Therefore, I present to you, my first Android app, 
Aldiko Sync that allows you to sync both your books and bookmarks across various Android powered devices.
** Note **
As of version 5.4.18, the app no longer requires a rooted device.
Older versions of the app are not compatible with this version, so please upgrade all your devices to avoid sync failures.
Thanks!
** Note **
Now available on the market: 
Requirements:- Android 2.1+
 
- Aldiko 2.0.2+ (Premium or Free)
 
- Dropbox account
 
Features:- Synchronizes eBooks across devices (including addition of new books and deletion of old books)
 
- Synchronizes your position in each eBook across devices.
 
- Pro Version: Fully automatic sync.
 
- Pro Version: Faster sync check for changes on Dropbox
 
- Pro Version: Trigger sync from an external application (like a Tasker/Locale plugin).
 
- Ability to store deleted books in a separate "TrashCan" folder on Dropbox in case you want to retrieve it at a later date.
 
- Ability to always sync to furthest read point (like the Kindle).
 
New Features:
- 7.0.4
- Add option to always sync to furthest read point.
 
- Improve code that checked for internet connectivity, should reduce  the "Unable to reach Dropbox" message when switching from mobile to  WiFi.
 
- Pro Version: Allow error notifications to be dismissed when the "Hide Status Icon" option is enabled.
 
- Bug-Fix: Detect and ignore incompatible thumbnail/cover images when adding new eBooks instead of failing the sync operation.
 
- Bug-Fix: Fix very slow loading of library data for large libraries  (100+ books) on devices whose default locale is not US English.
 
 
- 6.18.32
- Updated app to fix issues on Android OS 4.0 (Ice Cream Sandwich)
 
- Add option to always add books from a device to Dropbox on first sync (enabled by default)
 
- Expand info sent via the "Report Issue" feature for a better support experience.
 
- Bug-Fix: Fix the "eBooks Folder" field to be a single line control.
 
- Pro  Version: Improve license check code to reduce verification failure  reported by some users. Requires updated unlocker app to be installed.
 
- Pro Version: Update the "Hide Status Icon" feature to be more useful by displaying the icon when a sync is in progress.
 
- Bug-Fix:  (Pro Version) Fix issue where a sync was not performed if the device  went to sleep due to the screen being turned off before the trigger  could execute.
 
  
- 6.10.2
- Add extra checks to verify internet connectivity before starting a sync operation. With this change, the "Unable to login to Dropbox" message should show up only for actual Dropbox login failures.
 
  
- 6.6.14
- Correctly resize the cover/thumbnail image  when  adding a book to the device. Fixes issue with squashed images on   certain devices.
 
- Bug-Fix: Position in eBook was not being synchronized across devices if it had user defined bookmarks.
 
- Make it much easier to report an issue with the app (Settings => Report Issue).
 
  
- 5.10.4
- Bug-Fix: (Pro Version) (Android OS 2.2+) Fix crash on reboot when automatic sync is enabled and Aldiko is installed on the SD card. Correctly handle moving Aldiko from/to the SD card and SD card mount/dismount events.
 
- Bug-Fix: (Pro Verison) Fix crash if automatic sync is enabled when Aldiko is not installed.
 
- Bug-Fix: Fix issue with eBook getting updated on every sync on local device if it was deleted and re-added on another device.
 
- Pro Version: Reorganize code to improve battery life when automatic sync is enabled during a long Aldiko session.
 
 
- 5.8.20
- Bug-Fix: Discard stored local sync state if its incompatible with the new app. Fixes the "Unable to read library" error when loading previously synced books.
 
- Bug-Fix: Fix handle leak on screen orientation change.
 
 
- 5.4.18
- Rewrote core parts of the app so it no longer requires root access.
 
- Further improvements to the code that handles dropped connections during a sync.
 
- Bug-Fix: Fix issue with an eBook not getting the correct saved position under certain rare circumstances.
 
- Pro Version: Minor improvements to the "Optimize Network Traffic" feature.
 
 
- 4.1.2
- Updated app to work on Android OS 2.1 (Eclair)
 
- Improve handling of dropped connections. This should help reduce sync failures.
 
- Add feature to optimize data stored on Dropbox. This feature enables compression of the library data and speeds up the sync operation.
 
- Bug-Fix: (Pro version) Under certain circumstances, eBook updates would not be applied on a subsequent sync if the first attempt failed.
 
- Bug-Fix: Fix issue with icon in the status bar being stuck in the "on going" status even after the sync operation was complete.
 
  
- 3.4.2
- Bug-Fix: Inadvertently introduced a bug in the previous version, which could cause a manually triggered sync to loop infinitely under certain circumstances. (Sorry!)
 
- Pro version: Add ability to trigger a sync operation from external apps (like a Tasker/Locale plugin) via a broadcast intent (com.ucr.aldikosync.triggersync)
 
 
- 3.3.6
- Bug-Fix: Auto sync was not being triggered after quitting Aldiko on certain devices (some HTC phones, devices with CyanogenMod 7 ROM, and maybe others)
 
- Bug-Fix: The "Optimize Network Traffic" option is dependent on automatic sync being enabled. Fix the Settings user interface so this dependency is communicated to the user
 
- Add option to hide the notification bar icon in the Pro version
 
 
- 3.0.18
- Library handling code optimizations resulting in a smaller and faster app
 
- Improve reporting of Dropbox errors to the user
 
- Add support for fully automatic and faster sync checking in the Pro version
 
 
- 2.2.4
- Supports both Aldiko Free and Premium
 
- Fixes crash that some people reported with the initial release.
 
  
Please let me know if you have any questions/comments or concerns.
Thanks!