My mom's PhoeniX-ROM based Replenish was completely out of memory (with a constant "low memory" warning) which may have caused it to
crash and be unbootable. The USB port on my mom's Replenish doesn't work for data transfer so I couldn't implement
Firehak's data2sd hack for Phoenix-ROM which apparently moves all data to an EXT4 partion on your SD. (
Here's a direct link to Firehak's Goo download site. The data partition link contains a PDF with instructions.) So I installed Link2SD for free form the Play Store. I got an 8GB Class-10 SD card, created a 512MB EXT4 partion & 7.5GB FAT32 partition using a free PC program called called Mini Partition Wizard Home Edition. (Of course I copied the stuff on her old 2GB SD card to the FAT32 partion of her new 8GB SD card.) Then I set up Link2SD to use the EXT4 partion and moved most apps to that partion, thereby freeing up about 80MB of "internal" storage. That 80MB number is a bit misleading because there's actually still a few hundred MB available on the SD card too, so I guess that I could probably install many more apps if I linked them to the SD card.
There's a nice tutorial here. My mom's Replenish has 26 downloaded apps in addition to the built-in-ish apps like Maps, Music, Places, etc.) I was worried that some relatively-high-performance media apps (like Sprint TV, YouTube, Winamp, Pandora, Play Music & Groove IP) wouldn't work well from an SD card since SD cards should be slower than internal ROM, but all of those apps work perfectly. (I did overclock to 748MHz so I'm not sure if that made a difference.) For safety I left a few apps, like Titanium Backup & Where's My Droid on the internal memory so that if the SD card fails or is removed, I can still locate and restore the phone. Link2SD has an intuitive interface and is quite nice in its functionality for moving and managing your apps.
One thing that I noticed on my mom's phone was that her POP mail account was taking up 40MB of storage (I guess because of all the email in her inbox and sent mail box.) Apparently POP mail just builds up unless you manually delete it, whereas IMAP mail (like Gmail) caches a limited amount of mail on and off your phone, while keeping the rest on the server. (She has one Gmail account and unfortunately one legacy ISP-based POP mail account that I've been trying to get her to abandon for years, to no avail.)