besides dropbox, I opened another account at Wuala from Lacie, and by using the discount codes billow you can pimp up the quota to 12GB.
I hope you find it useful. On OS X you can integrate via MacFuse (32bit kernels only), or use the uploader/sync app.
I am not anyhow affiliated with Wuala.
1. download the app at
http://www.wuala.com/referral/JC74B7C3CGKPGB4MGP73
or just http://www.wuala.com
2. create a new free account
3. in the user menu > manage account > buy storage
4. start adding one by one the following discount codes (order doesn't matter):
PC-MAGAZIN (will make it a pro account)
I-KNOW-CAROLA
I-KNOW-DOMINIK
I-KNOW-FABIUS
I-KNOW-MARCEL
I-KNOW-LUZIUS
I-KNOW-THOMAS
I-KNOW-DARIO
I-KNOW-MARIUS
I-KNOW-JONAS