After reading this lengthy post and piggybacking on what a few others have said.
H-torch - I think everyone should have.
Numerous games including Bejeweled.
Groovefish 0.3.2- Fantastic new program for searchable streaming music. This way you do not have to guess which music she would like on her phone.
Rss reader set to the info she would like.
The usual facebook, twitter, other social media apps.
Something related to her line of work. (ie: If she is a nurse, get her a med calculator)
Something related to her favorite hobby. (Maybe the "Love Me" program is for her
)
Just as we all like to personalize our phones for our needs she would like her's personalized as well. ASK HER WHAT SHE WOULD LIKE. Make her feel special by making it about things she likes, and only you will be able to do that since you know her better.