Есть какой нормальный бесплатный GUI для S3?

да, называется браузер

Нет доступа к панельке. :)

eix -c -S amazon

[N] app-admin/amazon-ec2-init ((~)20101127-r1): Init script to setup Amazon EC2 instance parameters
[N] app-admin/aws-cw-tools ((~)1.0.12.1): The API tools serve as the client interface to the Amazon CloudWatch web service
[N] app-admin/aws-rds-tools ((~)1.6.001): The Command Line Toolkit for the Amazon Relational Database Service
[N] app-admin/cli53 ((~)0.8.4): Command line tool for Amazon Route 53
[N] app-admin/ec2-ami-tools ((~)1.5.6): These command-line tools serve as the client interface to the Amazon EC2 web service
[N] app-text/getxbook ((~)1.0-r1): Download books from google, amazon, barnes and noble
[N] dev-haskell/aws ((~)0.12.1(0/0.12.1)): Amazon Web Services (AWS) for Haskell
[N] dev-haskell/hs3 ((~)0.5.9(0/0.5.9)): Interface to Amazon's Simple Storage Service (S3)
[N] dev-perl/Net-Amazon (0.620.0): Framework for accessing amazon.com via SOAP and XML/HTTP
[N] dev-perl/Net-Amazon-S3 ((~)0.800.0): Framework for accessing the Amazon S3 Simple Storage Service
[N] dev-perl/VM-EC2 ((~)1.280.0): Interface to Amazon EC2, VPC, ELB, Autoscaling, and Relational DB services
[N] dev-php/PEAR-Services_Amazon ((~)0.8.0): Provides access to Amazon's retail and associate web services
[N] dev-python/boto ((~)2.42.0): Amazon Web Services API
[N] dev-python/pyamazon ((~)0.65-r1): A Python wrapper for the Amazon web API
[N] dev-python/s3transfer ((~)0.1.9): An Amazon S3 Transfer Manager
[N] dev-python/simples3 ((~)1.0): A fairly simple, decently quick python interface to Amazon's S3 storage service
[N] dev-ruby/aws-s3 ((~)0.6.3): Client library for Amazon's Simple Storage Service's REST API
[N] dev-ruby/aws-sdk ((~)2.5.11(2)): Official SDK for Amazon Web Services
[N] dev-ruby/aws-sdk-core ((~)2.5.11(2)): Official SDK for Amazon Web Services
[N] dev-ruby/aws-sdk-resources ((~)2.5.11(2)): Official SDK for Amazon Web Services
[N] dev-ruby/litc ((~)1.0.3-r1): A tiny ruby module for Amazon EC2 intance metadata
[N] games-rpg/queen (1): Flight of the Amazon Queen - a 2D point-and-click adventure game set in the 1940s
[N] net-fs/s3backer ((~)1.3.7): FUSE-based single file backing store via Amazon S3
[N] net-fs/s3fs ((~)1.80): Amazon S3 mounting via fuse
[N] net-libs/libs3 ((~)2.0-r1): A C Library API for Amazon S3
[N] net-misc/clamz ((~)0.5): Command-line downloader for the Amazon.com MP3 music store
[N] net-misc/libres3 ((~)1.3): Skylable LibreS3 - Amazon S3 open source replacement
[N] net-misc/pymazon ((~)0.9.1): Downloader for the Amazon.com MP3 music store
[N] net-misc/s3cmd (1.6.1): Command line client for Amazon S3
Найдено 29 совпадение.

з.ы. я когдато net-misc/s3cmd юзал - вполне себе, но не гуй

s3 browser