Forklift, the split-pane file manager with support for multiple network protocols, is officially at version 1.5 now. We covered the initial release a while back, and we're excited about the progress it's made. With an interface update (Leopard goodness) and some behind-the-scenes tweaks, it's turning into a sweet piece of work.
Forklift has always been of interest to me, with its support for SFTP and Amazon S3, but my previous experiences with Forklift had shown it to display a tendency toward a little sluggishness and the occasional poorly-timed crash. This latest version has not only been stable for me, but has been snappy. And by that I mean speedy to the extreme, especially when dealing with (S)FTP servers and S3. Ten times faster on remote transfers, actually, according to their own benchmarks.
Quick Look and FXP Copy (server-to-server file transfer) round out a great feature set. If you're looking for a Finder add-on/replacement (or a great FTP client), definitely download the trial. At $29.95, it's quite reasonably priced for what it can do. And for current users the upgrade is free and will fix quite a few shortcomings you may have noticed thus far. Version 1.5 is Leopard-only, but 1.2 is still available for our striped friends.