GoodReader is also an option. You can import photos into GoodReader and then use it to upload them to a server like iDisk or DropBox. It is a little less trouble than the email option, since you select each photo with a tap, and there is no limit to how many photos you can choose at one time.
Photos can also be zipped into an archive. That will get around Mail's 5 photo limit, but the file might end up being to big to go through the servers.
iDisk costs money, of course, but you can set up a DropBox account for free. As long as you don't have more than 2GB of photos it would be tedious, but not hard.
Another possibility is to use an online photo service like Flickr or PhotoBucket. You can upload all your photos, and have access to them almost anywhere. They can be downloaded again later when you need them. But be sure to go into the app's settings and make sure you upload Full Sized photos, or you'll lose the original's quality. The app I use for Flickr is FlickrStackr. I don't know what the best PhotoBucket app is.
FlickrStackr will let you select lots of pictures at once, and organize them by album on the Flickr site. You'll need to set up a flickr.com account.
I'm sure there is a better solution. But I don't have any experience with the apps involved.